The Edinburgh Festival reserved its biggest operatic event for last. From St Petersburg, the Mariinsky Opera brought a production of Berlioz’s Les Troyens that could truly be described as epic: a stellar cast, a vast trompe d’oeil set, and an overall duration comfortably over five hours. A large audience greeted it enthusiastically, but not ecstatically. Maybe exhaustion had set in: there were yawns and smiles in equal measure on the way out.

First, confessions. I’m the dance critic here at theartsdesk. Yes, this is a review of a concert performance of an opera, and no, I haven’t picked up a detailed knowledge of Rossini’s oeuvre as a byproduct of my education in pirouettes and Pina Bausch. I attended last night’s concert as a common or garden punter, and a chance one at that, taking a ticket to save wasting it after its original owner had to give it up because of a work commitment.

God it’s good to laugh in an opera house. Not a hear-how-clever-I-am-to-get-the-laborious-operatic-joke laugh, or an I-realise-this-is-supposed-to-be-funny-so-I’m-playing-along one, but a real, spontaneous laugh that tickles into sound before you’ve even had time to register its approach. Back for its second appearance, Robert Carsen’s Glyndebourne Rinaldo is ingenious and witty, joyous and completely over-the-top, and the best possible ending to this year’s summer opera season.

All kinds of narratives were at play in this Prom from the BBC Symphony Orchestra and its Principal Conductor Sakari Oramo - and perhaps the truly adventurous programmer might have double-deployed Rory Kinnear, dispassionately chronicling Stravinsky’s Oedipus rex, and taken us beyond the Overture and into the melodramas of Beethoven’s Incidental Music to Egmont.

“What does opera have to say to the under-30s?” asked Alexandra Coghlan on theartsdesk yesterday. The question “what does opera have to say to the under-10s?” has had to wait until today. For although yesterday afternoon’s performance of Will Todd’s newish opera for children of all ages was the last in its second, sell-out run on the Yucca Lawn behind Holland Park House, it seemed essential to make my four-year-old goddaughter Mirabel available for comment, and that was the only date available in her diary. The answer?

If last year’s Ring cycle triumphantly proved that world-class opera can be done at the Albert Hall, this Rosenkavalier suggests that the less epic end of the repertoire isn’t such a sure thing. That is not to say that this performance was dud, far from it; rather that its few problems were venue related. Balance was the main issue, though Robin Ticciati did a great job of whipping the London Philharmonic Orchestra into a passionate frenzy in the Prelude and then taking things down a notch and keeping them there to avoid engulfing the voices.

Some of us have witnessed Traviatas where single stars were born: Angela Gheorghiu for Solti at the Royal Opera nearly 20 years ago springs quickest to mind. Some would claim a dream couple in Anna Netrebko and Rolando Villazon on peak form at Salzburg. Yet how often in a lifetime do you catch an evening like this, where all three principals are not only up to the very highest vocal standards but also work as one with the conductor to make sense of every phrase, every word, in an intimate space for which Verdi's chamber opera might have been crafted?

One of the joys of attending an opera in the Concert Room at St George’s Hall, Liverpool, is the feeling that the audience is sitting in the set itself. Now one of the city’s foremost concert venues, this Victorian gem never ceases to amaze, even though it was reintroduced to active use in 2006 after extensive refurbishment. This summer and autumn, much of the Royal Liverpool Philharmonic’s musical activity has decamped to the venue as the Philharmonic Hall has closed for a multi-million pound refurbishment and partial rebuild.

Bakst’s harem drapes and Roerich’s smoking, steaming Polovtsian camp may not have had the most lavish of recreations. But the rest of this homage to Diaghilev shone with an exuberance and even a precision one would not have thought possible from previous seasons of what had once seemed like Andris Liepa’s Ballets Russes vanity project.

Buxton has gone Bohemian, digging into Dvořák’s treasure trove and celebrating Gluck’s tercentenary. The choice of Dvořák’s The Jacobin fits the Buxton Festival tradition of rooting out neglected works, since this has been unjustly overlooked since the first performance in 1889. It’s an irony that this makes Gluck’s Orfeo ed Euridice an unexpected choice, being ever-popular since 1762. However, artistic director Stephen Barlow has linked them for the festival’s two new home-grown productions for this, the 36th festival.