Honestly, I'm so busy most of the time that I like 12-15 hour range games. I don't know how much I like the constant push for a) multiplayer in everything; and b) that everything be so damn long. I just want the game to be good. If it can be good and long, great. If it's like UC2 or Batman: AA and the single player isn't super long, but incredibly well-crafted, then great, I'm happy. Too often games single player experience suffers from tacking on multiplayer or trying to unnecessarily lengthen it (while I personally loved Brutal Legend, this seemed to suffer from that).
Games like, say the Final Fantasy series I enjoyed back when I was in grade school because I'd actually have time to play them. Now if I try to start one, I either lose interest due to the awful stores they have now, or I have to put it down for a while and when I come back, I can't remember what the fuck was going on.