Once I get better at French:
I would go to Paris of the Romantic period. I would visit a salon, and I can imagine the scene:
Chopin and Liszt are playing a duet at the piano, probably Chopin at the bass, Mendelsohnn might be turning the pages, Schuman, wife clara, and Fanny Mendelsohn might also be there, I might be able to commision a portrait with Delacroix and I have always wanted to talk to Alexandre Dumas, and I could see Thalberg, Dreyshock, and Liszt play at concerts later on.
I would, as a second choice, like to see Beethoven to get a kick out of his temperamental behavior and disorganisation, and as a last choice...hmm..I would like to see Mozart as a boy, but also as a man..and I could see Haydn and Clementi then as well.
It would be fun to see J.S.Bach's duel with the basoonist, and I'd like to see William Byrd so I could also also see William Shakespeare.