If we finish early, I like to try to do it right after the session. I'm constantly trying to balance the issue of too much combat versus too little, so I try to check in with the players to find out if they liked the balance during that particular session. We also chat about the "cinematic" feel (or, lack thereof) of the session. The players also try to give tips about my portrayal of NPCs and such.
We also discuss it between session on our message boards, although truth be told, I usually only get one player, at most two, who participate.
Cool - In just two and a half years, I've reached 2% of Crothian's total post count.