THE MAN in front of me, walking down an Islington street towards the Almeida for the first night of Who's Afraid of Virginia Woolf?, had short grey hair, spectacles and hunched shoulders. He looked surprisingly tense. According to a programme note, Edward Albee has seen 100 productions of this show. Aged 68, he wrote his most famous play in 1962. That's exactly half a lifetime ago for him (a whole lifetime ago for some of us). There's always a moment when a modern classic can slip a category and become a historical curiosity. Perhaps that explains Albee's hunched shoulders. If so, he can relax. This definitely isn't the moment.

Who's Afraid of Virginia Woolf? doesn't immediately feel like a Sixties classic. It feels like a Fifties one. The tall dark bookcases and comfy leather seats - broken up in John Napier's penumbral living-room set by a backdrop of New England trees - returns us to post- war America. It's in this academic slough that George and Martha construct their fantasies. More than most, Who's Afraid? earns the title of "play". Half of what they get up to is a game.

George, a history professor, and Martha, his older wife, return home at 2am, followed by two other guests from the campus party. Caught in a crossfire of fantasy, malice and insight, these guests provide a captive audience for the George and Martha show. We find ourselves watching two actors playing characters putting on an act. Howard Davies's slow-burning, gripping revival contains one of the most spellbinding performances of the year.

It is not, unfortunately, Diana Rigg's. Her career has altered considerably from the days when she wore beautiful clothes and dished out elegant ironies. As if becoming one kind of dame (in 1994) wasn't enough, Rigg has also become another: a barnstorming Broadway madam. Last year, at the National, this pugnacious, lipsmacking bravura proved a triumph in Brecht, but Martha is not Mother Courage. Rigg brings an Olivier-sized performance to a play described by Albee as "(almost) naturalism". The external details assure us that everything is in place: she growls and barks, flaps her hands and sinks her nose deep into an ice-laden tumbler of gin. But the outbursts lack the visceral edge of a woman stung into response. It left me cold.

If Rigg is all mouth, David Suchet is all mind. Thin-lipped, balding, he pads round in his shapeless cardigan and unpressed trousers, cradling his drink and looking as sat-upon as the sofa cushions. Don't be deceived. Suchet delivers lethal remarks with lizard-like smiles. He suggests a complicated, endlessly fertile mind that's scarily difficult to gauge. Whether playful or sincere (and Suchet creates moments of chilling, almost poetic intensity), the two spring powerfully from the same source.

Who's Afraid? is a large play with a small cast. The success of Davies's production relies just as heavily on excellent performances from Lloyd Owen, as the conceited young biologist who becomes increasingly unbuttoned and callous as the evening progresses, and Clare Holman, as his simpering, dizzy wife, whose remarks become more and more off-the-wall as the brandy kicks in.

Robert Lepage and Ex Machina's The Seven Streams of the River Ota, which has been developed over three years, and has three different running lengths, reaches the National in its longest, eight-hour version (with intervals, supper break, etc), where it runs for another week. In range and ambition, Seven Streams rivals a fat novel, a fractured, multi-layered one, that presents a composite story from a number of angles. Pity the person who has to write the programme synopsis.

Here's the outline itinerary: we move from Hiroshima in 1945, where Luke, an American army photographer, comes to document the physical damage of the bomb (and fathers a second son), to New York, 20 years later, when the two sons - both called Jeffrey - find themselves living in the same brownstone. We move, too, from Amsterdam in 1986, where the American Jeffrey, now suffering from Aids, has gone to receive an assisted suicide, to Terezin in 1943, where a young Czech girl escapes deportation. In 1970, we're in Osaka, where a theatre company from Quebec is touring a Feydeau farce. We return, in 1997, to Hiroshima - to the house of act one (where the River Ota divides into seven streams), where a third generation meet.

Lepage uses a liberating variety of techniques and genres (puppets, farce, film footage, etc), which constantly feed in and refer back to one another. Highly sophisticated and assured scenes present witty and moving stories against a grand historical backdrop. Seven Streams is a work of collaboration: 12 members of the company are also credited as authors. It suffers, if anything, from too much going on, which leads to fuzzy thematic connections. How does the dropping of several kilos of uranium in August 1945 connect with the spread of Aids in the 1980s? It doesn't. But the cast realise these intricate scenes superbly. To name only three examples: Anne Marie Cadieux's New York landlady has the cruel audacity of a Toulouse Lautrec; Richard Frechette brings a lugubrious comedy to the sly, philandering diplomat, and Ghislaine Vincent has a genial dignity as the Czech who becomes a Zen monk. See it once and you will want to see it twice.

In the last couple of weeks five plays have opened referring either implicitly or explicitly to atrocities committed in the Second World War. The most recent, Ronald Harwood's new play, The Handyman, is easily the worst. A 78-year-old man, a former member of the Galicia SS, a man accused of participating in the murder of 817 Jews, is also dear old Romka, who has worked for 50 years as the odd-job man for an English family at a Sussex country house. He cooks, sews, mends fences, cuts hedges and grows vegetables. A useful, lovable man, Romka is described by Mrs Field (in one of the play's vulgar ironies) as "a life-saver".

The change in the law over the prosecution of war criminals means that Romka, a stooping white-haired figure, played with a fittingly appealing Eastern European accent by Frank Finlay, finds himself cross-examined by two detectives. Poor Finlay has little to say, except he can't remember, it's not true, he's innocent.

In the interview room, the police produce statements from witnesses, who appear, in Christopher Morahan's stolid production, behind a transparent screen. We listen, queasily, to descriptions of murders, not knowing if they are literally true, and not liking (either way) to hear them recounted so crassly. The Handyman offers little action, or character development, and plenty of wooden comment: "I'm going to give it to you hard and I'm going to give it to you straight," says the lawyer, before she explains anti-semitism. By raising these issues in a numbingly pedestrian way, The Handyman only diminishes our response to unspeakable events.

Theatre details: Going Out, page 14.