Two - generally one rifle and one handgun. One of them is usually a .22LR, the other is something centerfire. If the wife is coming, I might pack an extra handgun, but I generally don't have room for a second rifle.
I agree with whomever said that time alone is probably not really a good measure of how much skill you're accruing on a particular range trip... I generally find myself improving the most when I slow the hell down on pulling the bang switch and really concentrate on taking perfect shots.