My boyfriend technically has a Lit account that he almost never uses, so if I were to cheat a little, I'd love to go to Paris with him.
As for actual Litsters, I think I'd go to London with ConstantineIII, to meet him in person and get to know him better.
Probably seems a bit cliche going down the London and Paris route, but those were the two places that really came to my mind first with each of those people.