My extremely fabulous mate Cat (note: name sharing not always mandatory in order to be friend of Kat) is singing in Orfeo at the ENO soon and as a) she's really good and b) she's playing a nymph (no sniggering! Infants, all of you.) you should totally go and see it. The Colosseum's ceiling is utterly staggering, and seeing as the only even vaguely affordable seats are in the balcony, you'll be getting very well acquainted with it, plus Orfeo has the dual benefits of being really good and pretty short so even the philistines among you won't get bored.