Count Zero – with you on La Wally & Diva connection.
Janacek – Cunning Little Vixen, not your average opera – couple others by Janacek – e.g. Jenufa – worth a look
Magic Flute – cracking tunes, hard to accept storyline..
Cosi Fan Tutte – drags on a bit (so does Marriage of Figaro IMO) but cracking characters.
Marriage of Figaro is quite a thought provoking work too, quite sad in places
Surprised no-one’s mentioned Britten, — Peter Grimes? Midsummer Night’s Dream
Wagner in parts – takes a while though 🙂
If you can get to one of these one piano opera condensed performances, they’re great – cast of maybe 6 or 7, accompanist, you forget there’s not an orchestra soon enough.