Marin bikes are the way to go, I just picked one up for 200 bucks (retail 400) and it is a dream. I had a 120 dollar wal-mart mongoose dx50 or something, but my marin "Bolinas ridge" is by far the best bike I've ever ridden. *the frame* It weighs about 10 pounds, has a quick-clip on the front tire, and is what is considered a hybrid of mountain and road bike. It only has front shocks, but I hardley even notice a difference... except when riding uphill. The back shock on the mongoose robbed all of my power and didn't provide that smooth of a ride. My vote is with Marin.
*Reason for edit* The 10 lbs thing is jus to show that it is REALLY light,the bike in its entirity is probably more like 20. Sorry for the improper number there, didn't mean to get on anybodies nerves.
http://www.marinbikes.com/bicycles_2...nas_ridge.html
^^^ specifically my bike.