Ivanov, Wyndham's, LondonSmall Craft Warnings, Arcola, LondonRain Man, Apollo, Shaftesbury Avenue, London

Everybody is caterwauling, yet we're at a wedding. Chekhov's early play, Ivanov, is an extraordinary roller-coaster of comedy and grief. In the last act of Michael Grandage's West End production – starring Kenneth Branagh – the titular despondent gentleman-farmer enters his young bride's family home to be greeted by a farcical cacophony.

His wavering betrothed, Andrea Riseborough's Sasha, is bawling along with her mother – who's heartbroken about parting with a dowry – and her completely discombobulated father, Keith R McNally's vodka-soused Lebedev. By the close of play, this is a genuine tragedy. Believing there is no chance of happiness regained, Branagh's Ivanov pulls out a gun.

Grandage's staging does not induce quite such extremities of celebration and despair. However, Ivanov is kicking off his Donmar company's big-name residency at Wyndham's (with Derek Jacobi, Judi Dench and more to come), and it's heartening to see more commercial playhouses concertedly raising their standards. What's more, much in Ivanov is highly enjoyable. Tom Stoppard's new English version is vivacious. Cheeky modern colloquialisms rub along with the fin-de-siècle Russian setting. Lorcan Cranitch is entertainingly rumbustious as Borkin, Ivanov's estate manager who tries to cajole the "chronic gloom merchant" into endless money-making scams. Malcolm Sinclair is rather splendid as the skint, devil-may-care Count Shabelsky. Tom Hiddleston also shines as the sanctimonious young doctor, Lvov, who is treating – and perhaps covertly adores – Ivanov's tubercular first wife (Gina McKee).

That said, several of the cast play their roles with an exaggerated gusto that belies, at points, all the talk about this backwater being cripplingly dull. A swifter and sharper sense of moral shabbiness, spite and deep despair is needed.

Branagh does not persuasively convey the numb lethargy of depression either, exuding an air of robust health. Nonetheless, his flashes of irritability and tender warmth are startling. There's an additional neat twist in having this actor – a famous Prince of Denmark – play this weary, provincial "hand-me-down Hamlet". Moreover, he will be directing Jude Law in Shakespeare's tragedy, to round off this Donmar West End season, in 2009.

Meanwhile, in the East End, the Arcola has become one of London's most enticing fringe theatres, presenting forgotten classics with outstanding casts and, sometimes, long-lost legendary directors. Bill Bryden now stages Tennessee Williams' Small Craft Warnings, set in a Pacific Coast bar strewn with booze-sodden drifters. Greg Hicks is mesmerising as Quentin, the dandyish, caustically sardonic gay scriptwriter who lurks in one corner with a boy he has picked up on the road. He is almost satanically jaded but also, like Ivanov, lamenting the death of the heart. Sian Thomas is engrossing as the brassy attention-hogging bar-fly, Leona, who clings to romantic memories. Her smirking macho man, Steve Nicholson's Bill, is chillingly callous and homophobic while Meredith MacNeill's scrawny, twitchy Violet – mentally challenged and on the skids – is hilariously infantile and poignantly decrepit. Worth catching.

Finally, back in the West End, a stage version of the Oscar-winning Dustin Hoffman road movie Rain Man might sound like a dumb idea. You never even see the vintage Buick in which Josh Hartnett, as the disinherited hustler Charlie Babbitt, roars across the States with his kidnapped autistic-savant brother, Adam Godley's Raymond.

And yet Dan Gordon's adaptation, directed by Terry Johnson, remains faithful to the fine original script while condensing the siblings' explosively dysfunctional, slow-bonding relationship into a chamber play. Hartnett doesn't quite cover the emotional ground that Tom Cruise did in the film. But Adam Godley is wonderful as Raymond. Gawky and stooped like a wizened elf, he is funny, robotically obsessive and strangely adorable.

'Ivanov' (0844 482 5120) to 29 Nov; 'Small Craft Warnings' (020-7503 1646) to 18 Oct; 'Rain Man' (0844 412 4658) to 20 Dec