If I were a rich man, I would back a London transfer of Fiddler on the Roof. Henry Goodman is on delightful form playing the impoverished dairyman and henpecked father, Tevye. Set in a Russian Jewish shtetl circa 1905, this darkening comedy sympathetically explores the tensions between staunchly traditional ways and the rise of more liberal, revolutionary ideas - before the community is shattered by a pogrom. Refreshingly too, Lindsay Posner's production of this Broadway musical is no lavish showbiz affair. Peter McKintosh's wooden set has a beautiful simplicity: skeletal houses cobbled together from weathered beams. When a train station is required, a few floorboards rise to form a track. Jerry Bock's score, newly arranged by acclaimed composer Sophie Solomon, also gains authenticity and intimacy, getting back (if not 100 per cent, at least much nearer) to its klezmer roots. The titular violin is wonderfully melancholic yet vibrant, accompanied by little more than a perky accordion, a flute and a couple of sinuous clarinets.
Goodman's Tevye often appears to be just casually singing under his breath, as if thinking aloud and burbling to a tune by chance. Silver-bearded in his peasant boots and cap, with sparkling dark eyes, he combines charisma and a lovely shrugging humour. His chatty grumbles, addressing God about his thankless lot, are touchingly human and very funny. This show is not entirely free of schmaltz or sentimental nostalgia. Beverley Klein and Julie Legrand teeter on the irritatingly caricatured as Tevye's testy wife and the fussing village matchmaker, Yente - with enough gesticulations to dock a taxiing plane. Technically too, some of the lyrics need sharper articulation and the lurid dream-sequence lighting is obtrusive.
But in our current climate, this revival looks almost startlingly brave, with its opening scene proudly celebrating religious garb (covered heads and prayer shawls) and arranged marriages - although, of course, Tevye's daughters soon start telling him exactly who they have decided to marry. The Sabbath rituals are absorbing, recreated with quiet care, and the wedding dances are a joy, choreographed by Kate Flatt with wine bottles balanced on Homburg-style hats.
Based on Sholem Aleichem's stories, Joseph Stein's book builds into a moving saga of mass emigration - with complex reverberations as the persecuted Jews head for Poland, America and Israel. This also looks, in the poignant final scene, like the play Chekhov never quite wrote, with an ethnic underclass mournfully packing their suitcases.
Initially, it seems Patrick Marber isn't even going to include the fear of God in Don Juan in Soho, his new cosmopolitan update of Molière. Instead of a 17th-century debauched free-thinker, here we have Rhys Ifans's arrogantly swanky DJ: a coke-snorting, sexoholic aristo prowling around Dean Street in 2007. He looks like a cross between Peter Cook, Withnail and Russell Brand, dandified in a slithery satin shirt. His scruffy dogsbody, Stephen Wight's Stan - who stores DJ's list of conquests on a BlackBerry - isn't religiously nervous about hell-fire like Molière's manservant. He is more outraged at Juan's antisocial selfishness. The punitive supernatural statue ultimately turns up pedaling a touristic rickshaw. So Ifans's stoned final trip through W1, essentially, represents his social spiral downwards towards a personal hell: a lonely, violent death on the streets.
Sometimes Marber is straining to be up-to-the-minute and Michael Grandage's staging has disappointingly rough edges, including one feeble commedia brawl and curiously lame special effects. Nonetheless, this variation on the myth becomes increasingly intriguing. Ifans has terrific outré flamboyance and a paradoxical feverous iciness. He seems spiritually empty, just golden-haired and glitteringly superficial, yet with flashes of satanic malignity and suppressed fears. Religious beliefs do subtly slip back in, with Marber's Muslim beggar who refuses to blaspheme. And by the end, Ifans' DJ, with his decadent vicious egocentricity, looks alarmingly like the worst aspects of London today, incarnate.
Lastly, the US playwright John Kolvenbach is back in town, alas. His previous banal, schematic homecoming drama, On an Average Day, surely should have been sufficient torture. But now we must endure Love Song, his banal, schematic combo of sitcom and romantic slush. How does he manage to lure stars to perform this stuff?
A winsomely cranky Cillian Murphy (from The Wind that Shakes the Barley) plays Kolvenbach's sentimentalised lonely hero, Beane, who is supposed to be mentally unstable. He starts off crouched in his poky apartment with the ceiling surreally sliding down, as if to crush him. John Crowley's production then executes a neat coup de théâtre as we cut, from there, to the airy designer kitchen owned by Beane's rich, bossy and manic sister, Joan (Kristen Johnston from Sex and the City).
OK, Johnston has a droll Miss Piggyish swish about her and Michael McKean is very likable as her wry, long-suffering spouse. But back at Beane's digs, he has suddenly acquired a dream girlfriend, Neve Campbell's modelesque burglar, Molly, who falls for his non-materialist lifestyle. She and Murphy then launch into enamoured rhapsodies, wallowing in dire prose-poetry and cringe-worthy pretending games. One longs for the ceiling to pulverise them both before they bore everybody into the ground. Painful.
'Fiddler on the Roof' (0114 249 6000) to 20 Jan; 'Don Juan in Soho' (0870 060 6624) to 10 Feb; 'Love Song' (0870 060 6627) to 3 Mar