During one of the intervals at the Swan Theatre in Stratford, a woman near me said: "I'm sure if we took some drugs, it would all make sense."

For Camino Real, Tennessee Williams's allegorical dream play - the first Williams the RSC has staged - is an intensely personal, hallucinatory play that is highly demanding of its audience. Demanding, in this context, means a show that doesn't have much plot or character development and still runs at three hours long.

On stage this elusive, seaport pageant, about - in effect - caged birds that find either companionship, love or death, emerges alternately as whimsical, camp, poetic, gaudy and profound. If only you could get your hands on whatever the author was smoking.

The plaza at the Camino Real spreads out round the Swan auditorium - in the dustily evocative designs by Yolande Sonnabend - as a crumbling sprawl of hotel balconies, neon lights and iron railings. It is populated by legendary characters: Don Quixote, Sancho Panza, Casanova, Esmeralda, Byron and Marguerite Gautier. Steven Pimlott's energetic production is also populated by several well-known actors: creating a neat mix of fame and legend. Leslie Phillips looks perfect as the wordly, linen- suited Gutman, owner of the hotel and master of ceremonies, a cummerbund containing his portly stomach, and dry, sinister laughs emitting from the back of his throat. Peter Egan is highly effective as the crisp, powdered Casanova, losing his wig and then his heart. Best of all, Susannah York as Marguerite Gautier brings an exquisite sense of fading beauty to the plaza. Here is a woman who must rely more and more on the kindness of lighting technicians. York's huskily desperate attempts to get money, tickets and papers for the Fugitivo, the plane that occasionally helps people escape the plaza, is the evening's high point. Elsewhere, Camino Real feels as if Williams has emptied his own private fancy-dress basket onto the stage. It is full of theatrical events and effects: shootings and seductions, a fiesta, a chase and a fight. But spending the evening with a bunch of archetypes is an acquired taste.

Adrian Noble opens his Cymbeline (on the main stage at Stratford) with an ingenious device. Whereas Shakespeare packs some dense exposition - about banishment, loss of twins, wicked stepmother, etc - into a conversation between two obliging gentlemen, Noble gathers white-cloaked figures around a flame that issues from what appears to be a wok. Here, as the saffron- robed soothsayer (John Kane) unfolds his tale, one by one the actors throw off their gowns and reveal themselves as resplendent characters in his drama. Short of each of them wearing name tags, it couldn't be more helpful.

And we need the help. For Cymbeline, a late romance with a long and convoluted plot, is performed so rarely that the New Penguin Shakespeare - a so-called complete edition - has yet to include it. In Noble's colourful if antiseptic production, the Pied Piper's desire - to make sure we're all following - dominates. A thousand lines have been cut; at three hours, this Cymbeline is a snip.

Anthony Ward's spare and sumptuous design transports us economically between Cymbeline's palace, a room in Rome and a Welsh cave, by means of a billowing sheet that spreads out across the floor or curls up towards the roof. This ancient Britain has a distinct oriental feel. When servants run on, they take little steps in their espadrilles, and bow with their hands clasped in front. The soldiers, with wide belts and thick robes, suggest Samurai warriors, and half the battle sequences take place in silhouette, against the white sheet.

The performances are more puzzling. RSC Associate Joanne Pearce is pushing it a bit to play Cymbeline's daughter, Imogen. When she scampers down the white carpeted aisle shouting "Take me to Milford Way!", we admire the effort more than thrill to her youthful ardour. As her father, Edward Petherbridge presents a complex, weary and sometimes indistinct portrait of a compromised king, a lopsided crown sitting on his long white hair. Guy Henry has an uneasy and fitfully rewarding task as the jingoistically foolish son, Cloten, only partially managing to mask his natural ironic intelligence. While as the scheming Iachimo (whose efforts to get inside Imogen's bedroom and note down all the telling details would earn him royal-reporter status on a tabloid), Paul Freeman is a raddled, smiling roue: a shallow, malevolent man.

When this late romance turns supernatural, with the appearance of deceased parents, a golden-headed Jupiter and a magically intricate denouement, Noble leaves us only amused. Sadly, the bold promise of that innovative opening sequence is never regained.

When you hear that the diminutive Kathryn Hunter is going to play King Lear, you wonder who they will find to play Cordelia. Hunter is a tiny Lear. Either of her daughters can sit on a bench and still look taller than their father standing up. Strangely, this works to Hunter's advantage. Her tyrannical authority only exists in so far as it is accepted by others. Take away that fear of her and this spidery, frail autocrat is impotent.

Helena Kaut-Howson's strange, driven and compelling production at the Leicester Haymarket is poised halfway between the dazzling and the baffling. We open with Lear in a wheelchair, completely gaga. EastEnders is on the TV, and Cordelia (an even tinier Hayley Carmichael) and the Fool (a jarringly benign Marcello Magni) are in attendance. Nurses purposefully cross the stage. Suddenly Lear collapses, gets rushed into an intensive- care unit, and dies. When the screens are pulled apart, Lear is revealed sitting on a trolley, in a baggy three-piece suit, crown on head, and swathed in red cloth.

This Lear hobbles round the stage with a walking stick, rasping out instructions with rolled "r"s, demanding attention with an Ed-wardian sprightliness. As the play develops, Kaut-Howson mixes the ancient and modern - trolleys and ladders become bracingly non-naturalistic props in medieval Britain. Tyres with broomsticks make windswept trees; when Edgar becomes Mad Tom, he hides from his pursuers in an old bath; when Lear brings in the dead Cordelia, rather than carry her he pushes her in a wheelchair; and when the French army is repulsed, pans, buckets and soldiers hurl across the stage. If this isn't a very coherent Lear, it is a defiantly stimulating one.

In St Nicholas, a two-hour monologue written and directed by the very talented 25-year-old Conor McPherson, Brian Cox conjures up an entertainingly horrific portrait of a Dublin theatre critic, who will review a show badly, then join the actors in the pub and let them know, just for the sake of a good evening, that he has reviewed it well. Half the pleasure of St Nicholas lies in Cox's masterful performance as the bleary, paunchy, self- loathing hack. The other half lies in the slow, relaxed and hilarious anectdotal style in which the critic recounts his adventures in pursuit of one of the actresses. You could listen for hours. It's only when St Nicholas changes gear and turns surreal, with the critic falling in with a group of vampires, that the monologue falters. The arrival of the vampires seems to have sucked some of the blood out of Cox's own ripe character and what we hear sounds more and more like the author's own, younger, voice.

Theatre details: Going Out, page 14.