NEW YORK — Tolstoy reminds us that every unhappy family is unhappy in its own way. But from Oedipus Rex to King Lear to Long Day’s Journey into Night, the great works overflow their clannish particulars to become universal. Eugene O’Neill’s Pulitzer-winning "play of old sorrows," which is currently enjoying a monumental revival on Broadway, could not be a more specific rendering of the playwright’s own family crucible: four loving, tortured souls sunk in a sea of drink, drugs, coastal fog, and interlocking recriminations. Yet it’s impossible not to have your heart broken by O’Neill’s Tyrones. By contrast, British playwright Peter Nichols’s 1967 A Day in the Death of Joe Egg, also on Broadway in an expert revival and also based on personal experience, is more closely moored to its time and circumstances. You feel the caustically rendered pain of the play’s central couple, who like the playwright have had lives and love upended by the care of a severely handicapped child. Yet in the end, the play does not, like Long Day’s Journey, wrap its individualized digits around you like a fist.

The Long Day’s Journey revival is, as the Bard (an Irish Catholic, according to James Tyrone) would say, the stuff that dreams are made on. Director Robert Falls, who helmed the 1999 Tony-winning revival of Death of a Salesman, fields a cast that once again features that fragile bulwark, Brian Dennehy, along with Philip Seymour Hoffman, Robert Sean Leonard, and the incomparable Vanessa Redgrave. Except for Redgrave’s unusually mercurial Mary, on whom the play is centered, the production is more respectful than revelatory — a careful buffing rather than a recarving of Mount Rushmore. But its four hours (including two intermissions) are as exhilarating as they are exhausting, though exhaustion is part of the experience, the total immersion in O’Neill’s agonized forgiveness.

O’Neill completed his autobiographical masterpiece in 1940 and presented it to his wife as a wedding present (one even he acknowledged as "sadly inappropriate"), along with instructions that it not be seen until 25 years after his death. But with the playwright’s demise in 1953, the last of the Tyrones had become an actual, as opposed to a living, ghost, and Long Day’s Journey made its debut in 1956. True to its title, the play is set between breakfast and midnight on an August day in 1912 at Monte Cristo Cottage, where the O’Neill family summered between James Sr.’s stints barnstorming the country as the Dumas count for which the house was dubbed. The playwright renames his Irish-American clan the Tyrones, treating the character based on himself less brutally than he does the skinflint father, drug-addict mom, and dissipated older brother (leaving out, for example, that by the age of 23 he had already abandoned a wife and child). On this particular day, the family are confronted by O’Neill stand-in Edmund’s imminent diagnosis of tuberculosis as mother Mary retreats after two months’ recovery into her long-time morphine haze.

As is pointed out in Harold Bloom’s excellent introduction to the 2002 Yale Nota Bene edition of the play, O’Neill, albeit the quintessential American dramatist, owes more to Strindberg than to Emerson. Bloom also notes that, in Long Day’s Journey, the extensive stage directions are sometimes more eloquent than the longwinded dialogue. Falls is mostly faithful to them, the exceptions being, for the most part, inspired and even startling. In act two, Redgrave’s Mary, a fraying tigress, physically attacks her late-for-lunch husband. Later, when Edmund tries to make her confront his diagnosis, she goes after him, wildly pulling his hair, goading him to the chilling "It’s pretty hard to take at times, having a dope fiend for a mother!" In a production that dares to be operatic as well as domestic, this turns Redgrave rigid and sends a weeping Leonard sliding down her body to her feet.

It is ironic that, just as the wonderful Dennehy was almost upstaged by Elizabeth Franz’s quietly fierce Linda in Falls’s Death of a Salesman, here he’s almost upstaged by Redgrave’s more radical reading. Her willowy, white-haired Mary can be girlish, even mischievous; or her humor, like her arthritis-curled hands, can turn vicious. She repeats her accusations about a life lived in filthy trains and cheap hotels so quickly and unthinkingly, they’re like tired, compulsive recitations. And not only do her hands have a life of their own, clawing at her hair, her face, the walls, but that life often takes the form of fluttering across the tracks of old remembered piano pieces. What’s odd, since Redgrave’s performance is so riveting, is that the one moment of the production I did not believe was hers: the play’s final speech. O’Neill’s instructions are followed to the letter, from the white hair in pigtails to the dreamy stare, but the morphine-induced retreat into childhood seemed more technical than felt.

Dennehy’s James, by contrast, ages as the long day grinds on, his solid, vigorous patriarch sagging visibly as hope for the family’s salvation ebbs. He rises to James’s great aria about his impoverished childhood and the relinquishing of his youthful acting promise for lucre, though, and betrays throughout a touching bewilderment. Moreover, the heat between his James and Redgrave’s fragile Mary, even after 35 years of mutually destructive marriage, is palpable.

Laboring in the long shadow of Jason Robards, the terrific film actor Philip Seymour Hoffman is younger and healthier-looking than many a Jamie, a sharp-tongued alcoholic since his teens. And he brings some uncharacteristic but genuine merriment to the character’s nihilistic humor, adding delight and incredulity to the tale he tells on himself about embracing "Fat Vi," the least desirable tart in the local whorehouse. He also makes you understand, from the first scene, the older, less favored son’s wrenching, symbiotic connection to the mother whose retreat back into drugs is for him the last straw, the final betrayal, the ticket to fall.

When Leonard played Edmund 10 years ago for the Huntington Theatre Company, I found him too passive even for the least corrosive of the Tyrones. Here, Edmund’s despair vying with anger, his lean body convincingly racked, Leonard exudes a quiet, ironic intensity that gets him through even the awkward pantheistic reveries about merging with the sea and the godhead that he shares with his father in O’Neill’s long fourth act. "There’s the makings of a poet in you all right," the patriarch observes. To which the son who would become Eugene O’Neill replies, memorably, "No, I’m afraid I’m like the guy who is always panhandling for a smoke. He hasn’t even got the makings. He’s got only the habit." Which proves that in this disarmingly truth-telling work, there’s at least one lie.

You’d expect A Day in the Death of Joe Egg to be less a play for all seasons than Long Day’s Journey. Riddled with cripple jokes, it’s a work that in a less sensitive yet unflinching revival might get arrested by the political-correctness police. But in Laurence Boswell’s production, which has been imported from London’s West End along with stars Eddie Izzard and Victoria Hamilton, it’s poignantly clear that the play is not about the living death of the handicapped child nicknamed Joe Egg but about the life and death of a marriage.

The title character is a spastic, autistic 10-year-old who’s confined to a wheelchair and carried like a feed sack but is also, in the manner of The Elephant Man (and in the concentrated person of Madeleine Martin), angelically beautiful, her "fits" confined to lip smacking and a rigid, outstretched arm. Halfhearted teacher and Warholian artist Brian and caregiver Sheila cope with their daughter’s tragedy through Brechtian vaudeville routines shared with the audience that, though carefully scripted, seem in Boswell’s low-key staging not just fourth-wall-breaking but almost improvised. There are moments when the actors appear, like Shear Madness clowns, to crack each other up.

No wonder, then, that stand-up comic Izzard so suitably and subtly fills the role originated by Albert Finney (and played by Alan Bates in the 1971 film). Izzard’s Bri, manic yet deeply sad, is always on, whether addressing us as an unruly class or playing a series of oddball doctors and vicars to his straight-man wife as they recap Joe’s story. And he’s nicely matched by the limpid-eyed, husky-voiced Hamilton, who was nominated for an Olivier Award for her performance as Sheila, who must deal with a husband who is more of a child and a child who is — in the words of one German specialist — more of a "wegetable." Kittenish, exasperated, yet heartbreakingly maternal, this Sheila conveys with intensity the hope she cannot shake, a hope her husband can neither share nor bear.

Joe Egg’s second act, which reaches beyond the insular, unsalvageable world of Bri and Sheila, is more dated and conventional — though it does dare an Ortonian flirtation with euthanasia. Amateur thespian Sheila returns from rehearsal with mutual friends Freddie and Pam, he a bombastic do-gooder brought to full booming obtuseness by Michael Gaston, she a shallow stereotype who can’t stand anything "NPA" (not physically attractive). And Bri’s tweed-clad, sensibly shod old mum, played with purring unflappability by the excellent Dana Ivey, turns up to shed light on her nihilistic, increasingly erratic son’s immaturity, which, coupled with Joe’s relentlessness, eventually defeats him.

This past Monday brought the 2003 Tony nominations, and, no surprise, Long Day’s Journey and Joe Egg were ubiquitous. Both productions were nominated for Best Revival of a Play. Falls and Boswell were nominated for Best Direction of a Play. Santo Loquasto was nominated for Best Scenic Design for his towering barnboard set for Long Day’s Journey. Dennehy and Izzard were nominated for Best Performance by a Leading Actor in a Play. Redgrave and Hamilton were nominated for Best Performance by a Leading Actress in a Play. And Leonard and Hoffman will compete against each other for Best Performance by a Featured Actor in a Play.