Into the Woods, Open Air, Regent's Park London <br/>The Sun Also Rises, Royal Lyceum, Edinburgh<br/>S'Warm, Battersea Power Station, London

Stephen Sondheim's fairytale musical Into the Woods adds a sardonic twist to your happy-ever-afters. Combining the composer's droll lyrics with James Lapine's satirical book, this pastiche (from 1986) rejigs a medley of everyone's favourite bedtime stories, flashing lupine grins as it envisages what morally nasty slips and sorry codas could await those who take a walk on the wild side.

So, for instance, chasing up Cinderella's Prince Charming, post-honeymoon, we find he's a maritally bored bounder, nipping out to ravish the baker's wife in the thickets.

Regent's Park and Into the Woods were surely made for each other, though, the Open Air Theatre being a bewitching sylvan dell – perfect to help celebrate Sondheim's 80th year.

Timothy Sheader's strongly cast and stylishly fun production (designed by Soutra Gilmour) is staged on a fantastic tree house: a multi-storey maze of ladders, decks and staircases spiralling into the boughs high above. The narrator is also played by a young boy: a clever directorial conceit which helps justify the somewhat jumbled narrative. This troubled runaway tips out his rucksack of toys and starts telling himself stories that spring into full-scale life from the bushes around him.

Alice Fearn's Rapunzel sings way up in the branches, perched in an eyrie of twigs. She's a bit like Lewis Carroll's Alice turned goth, with a tousled peroxide blond mane, stripey stockings and white jackboots. Hannah Waddington as her possessive witch-mother is more like Miss Haversham crossed with Lloyd Webber's Phantom – all ruched velvet humps and a scabrous scalp. She hobbles to and fro on crutches, then magically whizzes up her daughter's rope of hair.

The giantess, who's on the rampage because her husband was slain by Jack, materialises 30-odd feet up too: a recycled-junk puppet with a dustbin lid and an old lampshade for eyes, with furiously bobbing umbrella-brows, and a booming voice supplied by Judi Dench. Meanwhile, down below, Michael Xavier's greasy-quiffed Wolf in a gore-stained T-shirt and leather coat, gets wantonly carnal with the bun-guzzling Little Red Riding Hood (excellent Beverly Rudd).

Maybe Into the Woods rambles; Mark Hadfield is mildly dull as the childless, questing baker; Sheader could go darker; and the very end turns sugary. Nevertheless, Sondheim's score – under Gareth Valentine's musical direction – is nearly always interestingly edgy: jaunty ditties with jagged disharmonies underneath; a lovely melody sprinkled with acid.

In The Sun Also Rises (The Select), the tormented beast in the bullring is snorting and pawing the ground, monstrously loudly. The Royal Lyceum really should be shaking as it charges, hooves thundering above the roar of the crowd. However, there's no actual flesh-and-blood bovine, of course, in this pared-down, sporadically inspired adaptation of Ernest Hemingway – performed by the avant-garde New York troupe Elevator Repair Service.

In Hemingway's celebrated 1920s novel, a clutch of American and British expats –in a haze of booze – head out of boho Paris for the fiesta in Pamplona and a bruising bust-up. The guys are all intoxicated by the alluring party-animal Lady Brett Ashley. However, she's a restless lost soul who flings them aside in favour of a young matador.

In director John Collins's staging, Brett's coterie remain forever in a cavernous drinking den. Its brown walls are lined with glinting bottles, and its trestle tables are strewn with winking glasses, some brimming with whisky.

This production is most engaging when it's punctuated by quirky clowning and wittily weird choreography. Swanky sommeliers dart from dark corners, juggling wine bottles like pistol-spinning cowboys, pouring the protagonists imaginary snifters in perfect sync with amplified glugs and splooshes. It's like Monsieur Hulot with a hangover, and a touch hallucinatory. Everyone also jazz-dances spasmodically, bouncing like mad rabbits, hands flapping – their backs to the audience in a blaze of yellow light.

That said, the supposedly climactic bullfight, when the matador's target is represented by a pair of horns stuck on a violently shunted table, isn't so thrilling. And, more crucially, this production is peculiarly feeble whenever it shifts into straight acting and narration. Kate Scelsa, as Brett, sustains a feverish gaunt intensity. However, Mike Iveson as the amorously frustrated journalist-narrator Jake Barnes gives such a lame, understated performance that sometimes he's barely audible. At over three-and-a-half hours, this adaptation wasn't select enough.

Finally, watch out for the bees. S'Warm is the first part of an epic environmental trilogy being devised by the National Youth Theatre, in collaboration with Complicite. This piece is an apocalyptic and poetically surreal expression of alarm about the world's ailing honeybee population, on which our food supply depends.

S'Warm is being performed as a flash-mob event at various London landmarks by a buzzing mass of 500 young actors, sprinting around in white beekeeper-style overalls, insect-like dark glasses and flowery swimming caps. Some shout through megaphones that time is running out, and others drum on industrial oil cans while a dying queen-bee sings a rock-operatic lament.

This show may be pretty rough round the edges and narratively nebulous, but the setting for S'warm's opening night was stunning: a windswept grey dustbowl at the foot of the derelict, brick cliff-face of Battersea power station. The mass choreography was also startlingly distressing: phalanxes of doomed youth – with nowhere left to run – just lay down, quietly dying in this wasteland as a jumbo jet cruised overhead, oblivious in the sunset.

'Into the Woods' (0844 826 4242) to 11 Sep; 'S'Warm' (ideastap.com/ swarm) Canada Square, London, today at 4pm