I'm hoping for Act II to be along the lines of Athkatla and its environs - one huge city to explore (Baldur's Gate, in this case) with a few smaller settlements and some wilderness areas thrown in. Right now it looks like we'll be resolving, or at least significantly advancing, the personal quests of Astarion, Gale and Shadowheart once we reach BG, plus getting reacquainted with all sorts of people we've already encountered in the game. I'm looking forward to it.
I'm a little worried about how they'll handle a PC who's from the city - are they going to acknowledge that at all? - but I'll just have to wait and see how they handle it.