To add to that, I've found a few things that make stretching easier...
-Back- I take the triceps pushdown rope and just wrap it around one of the machines to stretch. It's alot easier than grabbing a door knob or something.
-Legs- When stretching legs, it's better to wait until the end of your workout to stretch both your quads and hamstrings. I used to do them seperately. My hams first, then move on to squats, then stretch my quads. I used to cramp up a bit doing it this way. So instead I do them at the very end. I usually feel like puking towards the end of my workouts, but after the first stretch I feel tons better. No idea why...Probably because my body knows I'm done for the day.