+1 for a hitch rack. They are much faster to use, not only putting the bike on but attaching the rack itself -- mine has one bolt and it's on and off in less than a minute. Bike takes about 30 seconds to put on the rack. No worries about driving under stuff and scraping the bike off the roof (I would do it, too).
Several bonuses: less effect on gas mileage, racks with a tray for the wheels and a retainer are more secure than hanging racks and don't require wheel removal like most roof racks, and you can use the hitch for a variety of other things if you like, from small trailers to cargo racks.