^Half hour's too short. If you're getting a full workout (say completed sets of 5-6 different exercises) in half an hour, you need to raise the intensity. Aim for an hour including stretches and stay busy. I usually spend about 1.5 hours total on weights and very little of that is idle time (walking back and forth between supersets, changing weights or machines).
Do you guys really not tell people to get out of the rack when they're misusing it? It's been a while since I've seen anyone abuse the squat rack, but back in the McGym days, I'd go right up to them and tell them I needed to use it. I wouldn't yell at them, I'd just make a statement while pointing at various objects (always confuse your enemies) and give them the look. If they played dumb I'd suggest they could do that anywhere else. Your mileage may vary if you don't look like a veteran, but at the same time the only people who curl (or whatever) in the rack are newbies and dweebs.
EDIT: Read back to the previous page.... jeeeeezus big lifts with no belt? Hulk it's no wonder you're all fucked up conceptually. I don't think I've EVER seen serious lifters squat or dead heavy with no belt. If you're down at 2 plates for warmups, sure. Otherwise, it saves your back. That shit's no joke. Straps are fine if you're not gonna compete, I always use them for deads and heavy shrugs because my hands just don't keep up.