Don Giovanni, Holland Park, London<br/>Idomeneo, Coliseum, London<br/>Zaide, Sadler's Wells, London<br/>Simon Boccanegra, Royal Opera House, London

Compulsive philandering can happen anywhere.

In Stephen Barlow's Don Giovanni for Opera Holland Park, the Don does his in Victorian London. A single streetlamp points the way to a grand hotel, a cosy pub, and the blood-stained apartment where a dozen portraits of the eponymous libertine are arranged (designs by Yannis Thavoris). This is the world of the sensation novel and the scandal sheet, of public rectitude and private corruption, secret libraries and sorcery.

With lickety-split tempi, florid decoration and needle-sharp dynamics from the City of London Sinfonia under conductor Robert Dean, and a light-voiced, ensemble-friendly cast, Barlow emphasises the comic elements in Mozart's dramma giocoso. Even the hotel bell-hop is attracted to Nicholas Garrett's suave, silver-tongued Don, whose conquests are illustrated on a fold-out map by Matthew Hargreaves's Leporello as the desk clerk and chambermaid eavesdrop. The wedding party is a merry brawl of costermongers and seamstresses, while the roles of Zerlina (Claire Wild) and Masetto (Robert Winslade Anderson) are given new fibre, with class and money as significant as they are in the other collaborations between Mozart and his librettist, Lorenzo Da Ponte.

Prim and bespectacled until "La ci darem la mano", Wild's diminutive Zerlina is the biggest character and the biggest voice, not averse to selling her virginity or rifling the Don's corpse for money. Masetto's burning resentment of the upper classes is eloquently conveyed in his body language, while Thomas Walker's eyes show hardening suspicion and frustration as Don Ottavio. It is easy to see which one will have the happier marriage. Ana James's icy, duplicitous Donna Anna is merely the first liar in an opera of lies, less believable with each cascade of coloratura, Donna Elvira (Laura Mitchell) the only honest character, though too pathetic to be sympathetic. The Don himself remains an enigma, as much of an illusion as his gas-lit ghostly foe.

What would Mozart's mature operas have been like had he not met Da Ponte? Idomeneo is his only "reform opera", French in tone if not in language. Katie Mitchell's modern-dress production for English National Opera underlines its austere beauty, using the immaculately choreographed traffic of aides, assistants and waiters to illustrate the powerlessness of Idomeneo (Paul Nilon), Idamante (Robert Murray) and Ilia (Sarah Tynan) in a pitiless bargain.

Students of Mitchell's work will recognise certain tropes: the waltzing extras in Idamante's obbligato aria "Non temer, amato bene", the unscripted shout of "No! No! No!" from Electra (Emma Bell), dishevelled wild card in a muted and ordered society. Vicki Mortimer and Alex Eales's Crete is styled in expense-account beige, all marble and glass, Poseidon's angry sea visible through the windows, the cliffs a jaw-dropping wall of stone. Certain details jar – the slide-projector garden in Ilia's aria, the over-zealous clearing of plates and glasses – yet this is an unusual example of musical and dramatic seriousness in what has been a particularly gimmicky season from ENO. Edward Gardner has the measure of the architecture of the score, its Gluckian grandeur and blurted intimacies, and the orchestra play significantly better under him than under any other conductor. Bell is, of course, a triumph, singing with glorious elegance even while exploring a waiter's crotch with her big toe.

If pedal foreplay shocks you, spare your blushes and scroll down to Simon Boccanegra, for there is worse to come. Plumped out with material from three Concert Arias, the final quartet from Die Entführung aus dem Serail, and an Entr'acte from Thamos, Ian Page's completion of Zaide (the opera the 24-year-old Mozart abandoned for Idomeneo) features some of the most remarkable lines I've heard declaimed over an orchestral accompaniment.

With the original texts of Mozart's melodramas lost, Page commissioned Melly Still, Ben Power and Michael Symmons Roberts to write new English lyrics and develop a storyline. Here's an excerpt from Soliman's (Mark Le Brocq) Act II melodrama: "I've let a mongrel's shit-streaked tongue invade her silken folds." Here's another, possibly my favourite: "To women, love is like a lollipop." Which is easy to say if you're a gun-toting sex-slaver with wall-to-wall lovelies to torture and abuse. Though finely played under Page, with powder-dry gut strings and piquant oboes, and gamely sung by Le Brocq, Pumeza Matshikiza (Zaide), William Berger (Allazim), Andrew Goodwin (Gomatz) and the lovely Amy Freston (Perseda), Still's production is as dire as the libretto-by-committee.

Placido Domingo has been dropping heavy hints about retiring. The world's most famous tenor is officially nearing 70, and has recently undergone surgery for colon cancer, yet his performance in the baritone role of Simon Boccanegra at the Royal Opera House does not look or sound like the work of an artist who is ready to stop. If he seemed to be anticipating his reactions to Ferruccio Furlanetto's Fiesco in the Prologue, he was comfortable and authoritative as the troubled Doge, and tender with his daughter, Amelia (Marina Poplavskaya).

A burnished baritonal Verdi tenor is not the same thing as a Verdi baritone, but the character is in Domingo's soul and Elijah Moshinsky's bland 1991 staging – the one with the graffiti – makes few athletic demands. Back in the music that suits him best, Antonio Pappano's conducting is impeccable, the chording of the woodwind and brass heavy with pathos. Though Poplavskaya's voice is worryingly scuffed, Furlanetto gleams with health. In Domingo's former role of Gabriele Adorno, Joseph Calleja almost steals the show. Almost, but not quite.

'Don Giovanni' to 14 Jul (0845 230 9769); 'Zaide' 9 & 20 Jul, Buxton Festival (0845 127 2190); 'Idomeneo' to 9 Jul (0871 911 0200); 'Simon Boccanegra' to 15 Jul (020-7304 4000)

Next Week:

The Don is at it again. This time it's Gerald Finley who sings the vile seducer in Jonathan Kent's Glyndebourne staging of Don Giovanni