We play a 7-14 person unlimited re-buy tournament every week. We start with 5000 chips. 30-minute levels. Blinds go like this:
25/50; 50/100; 100/200; 200/400; 300/500; 500/1000; 1000/2000; 2000/4000; 4000/8000
It usually lasts about 3.5 - 4 hours. 30 minutes is a good amount of time for a level we find. Ours would be be better (but longer) if we added a 75-150 and a 400/800...but we don't for time considerations.
Also check out homepokertourney.com. And here's a link to the blind structures from the various events at the World Series of Poker. We're trying them out in a mega-tournament in a couple of weeks. You can adjust the level time to make a tourney finish in whatever time frame you want.
<font color="red">LINKY WINKY </font>