Merry Wives, The Musical, RSC, Stratford <br/> Dick Whittington, Barbican, London <br/> The Enchanted Pig, Young Vic, London

Simon Callow has always sounded immensely fruity and now he has the bodysuit to go with it. Waddling around in the RSC's new rejig of the Bard - Merry Wives, the Musical - his Falstaff looks like a Christmas pudding on legs, with lecherous tendencies. Stepping in at short notice (after Desmond Barrit sustained an injury), Callow splendidly combines an air of fleshy decadence with super-posh vowels, relishing the Fat Knight's speeches like a great gourmand of the English language. Gregory Doran's staging offers a handful of irresistibly silly visual gags as well. Matching the timber-framed set, Callow rolls up at the Garter Inn like an Elizabethan Hell's Angel, on a Harley-Davidson fashioned from seasoned oak. Judi Dench bustles around in a frizzy auburn wig as his still-smitten old flame, Mistress Quickly, and also creates one hilariously surreal moment when she is seen "yonder", dwarfing the pint-sized houses of the town's receding perspective and shrugging it off after a double-take.

That said, the attempt to make this farce more fun by padding it out with song and dance is a dismal failure. Composer Paul Englishby's medley of styles is so clichéd and cloying - mixing old airs and Broadway-style slush - that each time the orchestra strikes up your heart sinks. And Ranjit Bolt's lyrics are often more of a mouthful than a hoot. Alexandra Gilbreath's teasing Mistress Ford has sparkle and Simon Trinder's Slender is a scene-stealing fop. But really, Doran's whole cast are uncomfortably straining to amuse. Behind the eyes - and against the backdrop of rolling hills - they looked like scared rabbits on press night.

As for the Barbican, you may blench at this world-class venue deciding to put on a family panto, Dick Whittington, and asking Mark Ravenhill - of Shopping and F***ing notoriety - to script it. Just how alternative is this going to be? Will our principal boy end up being viscerally abused in King's Cross for slapping his thighs and prancing round in high-heeled boots? Or will he, in the accustomed manner, simply be made Lord Mayor?

The good news, at least for anxious parents, is that Ravenhill has relinquished all his hardcore edge, doffing his cap to traditional slapstick and woefully feeble jokes. In fact, this show, directed by Edward Hall, merely proves to be depressingly bog-standard. The audience on the night I attended were admirably determined to have a good time, but Roger Lloyd Pack's deadpan dame is sour and dreary, at odds with his day-glo outfits. Danny Worters as the cockney apprentice, Totally Lazy Jack, is cuter but basically reprises his dimwitted role from Market Boy at the NT, with added narcolepsy. Only Debbie Chazen rises above all this as the adorable, gargantuan good fairy, Bowbells, twiddling her toes as she floats above Lundern Ta-air-n like a gossamer puffball.

Both these productions are put to shame by the The Enchanted Pig, an astounding new piece of music-theatre inspired by an East European version of Beauty and the Beast. John Fulljames's high-calibre production is exquisitely designed by Dick Bird, with a palace of rusting mirrors. The Pig-Prince, whom his young bride Flora learns to love, looks like a savage warrior-cum-punky satyr in battered leather breeches, with a bristling Mohican and armoured nose ring. The Moon, who helps when Flora seeks for her lost husband beyond the ends of the Earth, is a young man in a silver helmet atop a lighthouse, wisely musing on how people change and sending light beams dancing round the auditorium. On an ingeniously simple pulley, our fearless heroine flies through the skies too, beaming happily at the Sun who lights her way with his gilded miner's lamp.

The overlong last act could be tightened up and John Dove's score is challengingly grown-up. In fact, this is a modern opera complete with recitative. Yet his mostly atonal music is, in fact, excitingly edgy and weirdly magical, with pulsing trombone and rippling harp. Alasdair Middleton's libretto has beautiful simplicity and wit too. With the odd fidget, the tiniest children seemed spellbound at the preview I saw. And how fantastic: the Young Vic giving ENO a run for its money, with a cast including John Rawnsley and Nuala Willis. Their vaudevillian duet as the hilariously dour but devoted oldsters, Mr and Mrs Northwind, is wonderful.

k.bassett@independent.co.uk

'Merry Wives, the Musical' (0870 609 1110) to 10 Feb; 'Dick Whittington' (0845 120 7550) to 20 Jan; 'The Enchanted Pig' (020 7928 6363) to 27 Jan