Honestly I don't spend much over 45 minutes when I'm in the gym, but I usually get about 6 exercises in and about 3 sets per exercise.
I end up doing two unrelated muscle groups back to back, so i'm not wasting time standing around waiting for a muscle group to rest.
Here's an example of a day where I'm doing mainly legs and biceps:
Squats (3 sets) ----- dumbell curls (3 sets)
Leg press (3 sets) ---- standing barbell curls (3 sets)
calf raises (3 sets) ----- ab workout utilizing incline bench, no less than 110 reps total over 3 sets
And usually do a final bicep workout with one of those seated machines, and maybe alternate that with the leg extension machine.
If I have a solid hour, this workout would have some back exercises thrown in.
Note that this workout is ideal for a gym that isn't too crowded, so you can go back and forth between two stations.