Personally, I'd love to take to the skies instead of drudge along an old, mossy cavern pit. *bleaugh!*

Also, dynamic leveling would be great too. In these areas, the party is given a collective "Sync level" based on the lowest-leveled party member, but enemies and quests give dynamic curved experience rewards to each party member individually, depending on his or her actual level. The enemies could have curved stats and levels that are based on the collective stats of the entire level-synced party. A lv45 can level up with a lv27 while the game still remains challenging. Or something like that, I dunno.