weights are cool and you can check the girlies out at the same time! the university gym i use is a bit of a hotbed.

what i do in the gym is this, other people probably do it differently:

row 20 minutes
leg extensions
hamstring curls (the one that works the backs of your thighs)
leg press
calf press.

3 sets of 10 reps each circuit and 3 circuits, so you do each exercise 90 times.

i know of people who won't do their legs in the gym for fear of damaging themselves but there's not much can go wrong if you're sensible.