We have a Yakima roof rack that we installed on our Element. The great thing about something like the Yakima system (Thule has similar one) is that it can be transferred to different cars - the same rack (crossbars, bike holders and wind fender thing), 5 years old, has been on 4 different cars now. Only thing is you usually need different towers for different cars (for our cars, we've needed Q towers for the sedan, specific towers for the station wagon that had factory racks that ran along the length of the car, and now for the Element we had to buy the "landing pads" and new control towers). But the beauty is that you always have your own crossbars so don't need factory installed bars on each new vehicle you buy.
The other alternative is a hitch mount. Our friends have the Thule hitch mount - the type that doesn't hold on at the frame (esp nice if you have a $$ bike). But that requires you either get the factory hitch or a mount it yourself hitch (like the Hidden Hitch, etc). That will be our next purchase for trips where we want to do road and mountain biking and have the dogs with us!
