AS OPERATIC TAKES on the eternal feminine go, Massenet's Manon falls mid-way between Verdi's Violetta and Tchaikovsky's Tatyana - somewhere around the Mimi mark and, by the natural law of these things, destined for tragic death. Straight out of school and into every listener's heart, she comes as close to an inspired creation as her tunesmith author ever got.

In the right hands and with the right voice, Manon is Massenet's ticket to repertory status. Without her, he'd be a minor figure of the belle epoque whose only lasting claim to interest is that he was technically adept, formidably prolific, and knew how to give the public what it wanted. But with her, and the score that bears her name, he soldiers on, dispensing charm like paracetamol, cheap but effective. And since charm is so central to what Massenet is about, it's an act of either courage or perversity (depending on your point of view) that ENO's new Manon has so little of it.

Standard productions of Manon are pure Fragonard. But this one, directed by David McVicar in his ENO debut, is pure Hogarth: bustling, Big Theatre, but dark and rather squalid at the edges. The sugar-coated passions of the piece are kept at arm's length by playing every act in something like an 18th-century bear-pit theatre, with an onstage audience of observers. And while that removes the whole thing from the stylistic world of opera comique, it's engaging and it works. I like this show, and like the way Paul Daniel, the conductor, makes Big Theatre of the score too. Massenet devotees won't, and they should keep away. But they'll be missing some outstanding playing from the pit, inventive choreography by Michael Keegan- Dolan, and some pretty good performances all round.

John Hudson isn't quite the matinee-idol Des Grieux, and he pushes his tone; but he does the Daydream Aria nicely. Ashley Holland's Lescaut is robustly likeable. And Rosa Mannion is a delight in the title role, the voice not quite settled in yet and a bit uneven, but delivering Classic FM golden moments like the Table Song with touching pathos. Thomas Beecham used to say he could swap Manon for the entire Brandenburg Concerti and consider it a bargain. An absurd comparison. But there were times during this unconventional show (which Beecham would have hated) when I almost understood what he meant.

If Manon is a fair swap for the Brandenburgs, Tchaikovsky's Eugene Onegin ought to buy both Passions and the B Minor Mass as well. To my ear, it's the perfect opera: lean and tender to the point of edibility, and something that I'd never never thought would find me looking at my watch - until, alas, along came Dalia Ibelhauptaite's new production at Opera North in Leeds.

In fairness, this is a tasteful show which tries to recreate the simple, spare intensity of Graham Vick's classic Glyndebourne reading. But though the simplicity and spareness come through well enough, with open sets, plain backdrops and just a few sticks of representational furniture, the intensity goes awol. Ibelhauptaite doesn't hit the spot. And she doesn't even smell the essence of the piece - which is its delicate, Jane Austen-like examination of great passions corseted by social niceties. Tension masses through minutiae until the dam bursts and emotions overflow. With Ibelhauptaite, however, there's no dam, no bursting: just a cast of badly-costumed characters (not one of whom looks as though he actually lives in his clothes) "doing" a production.

It's dull, it's empty, and the few things introduced to liven up the show largely misfire. There's a mysterious hanging box in the set design which I think is meant to house an emotional microclimate (blue sky for the opening, grey for the duel) but actually looks like a malfunctioning surtitles board. Then there's an embellishment of Monsieur Triquet's aria with magic tricks, which helps explain why everyone at the party is so taken with the old codger, but also distracts from the pure charm of the moment. The one (and only) nice idea is to bring Gremin back on as the curtain falls - an interesting variant on Onegin's open ending. You always wonder what will happen next. Ibelhauptaite suggests another gentlemanly punch-up.

Staying on the credit side, the chorus sing with vigour. Frances McCafferty handsomely turns the nurse into a leading role, with not a lawks-a-mercy in her. And Paul Nilon sings a good Lensky, even if the production strips him of Byronic energy and leaves him wimpish. But Onegin himself is disappointing. It's always a hard role in that it's so aloofly cool, but Peter Savidge makes nothing of it, dramatically or vocally. And Tatyana - well, she nearly comes off, but not quite. The true darling of opera (even more than Manon), flushed with the passion and hurt of first love, she has to sweep her audience through the torrent of the letter scene and make our hearts break with hers when she's rejected. Nothing less will do. And though Alwyn Mellor has a lovely voice and pleasing personality, there have been some outstanding Tatyanas around recently - Elena Prokina and Susan Chilcot - who set standards she doesn't meet.

As for the American conductor, Steven Sloane, I've mixed feelings. The big numbers - choruses and dances - are fine, and there are moments during which the orchestra sounds rich and full. But the tempi are generally sluggish and, like Ibelhauptaite, he can't make that dam burst in the letter scene. This show is critical for him - his first since he was announced as Opera North's next MD. What this production says for his potential there, I'm not sure.

When the Royal Opera's Otello transferred to the Royal Albert Hall last November, it was simplified into a sort of semaphore to cope with the conditions, while remaining recognisably the show that Elijah Moshinsky first devised. With La Traviata, which opened at the Hall on Tuesday, it's a different matter. Not much of Richard Eyre's original staging survives. There's no proscenium, just a disc-based apron stage. And there's nothing behind it to camouflage the organ, entrances and exits but a pinned-together job of muslin and bed-sheets that (a) looks cheap and (b) makes every scene look like it's happening in a sanatorium: not necessarily inappropriate to Traviata, but as piercing a proclamation of poverty as you could ask of international opera.

In truth, Traviata is too intimate an opera for arena treatment, and it's like watching a semi-staging through the wrong end of a telescope: Violetta might as well be dying on an ice-cap in the North Pole for all the contact you get with her. But that said, the first-night peformances (there are three alternating casts) were good, with two young leads of stunning promise. Elena Kelessidi, the Greek soprano who caused a stir when she sang Violetta at Covent Garden two years ago, begs comparison with Angela Gheorghiu for her mesmerising combination of fragility and power: a brilliant, gravity-defying top, and easy fluency throughout the whole voice. Her Alfredo is an Argentinian tenor, Marcelo Alvarez, of soft attack but cream-smooth tone and youthful freshness. And it's all comparatively honest singing: no head-mikes, just occasional, broad pick-up sound enhancement, subtly done although it tends to pick up ambient noise as well as actual music. The conductor was Simone Young, a convincing Verdian, strong and forthright. And apart from the bedsheets, I've only one reservation about recommending this arena Traviata (with this cast) to first-timers: there are no surtitles. Too expensive, apparently: but still an odd omission for a show edging itself into the world of people's opera.

'Manon': Coliseum, WC2 (0171 632 8300), Wed, Fri & to 18 Jun. 'Onegin': Leeds Grand Theatre (0113 222 6222), Fri to 26 Jun; then touring. 'Traviata': Royal Albert Hall, SW7 (0171 589 8212), Tues-Thurs & Sat.