Just a note about vertical hitch racks where the bike mounts vertically attached only by the fork... make sure your fork has "lawyer tabs" - the little bumps at the end of the fork that keep your wheel from falling off if the quick release isn't tight enough.

A friend's bike fell off a rack of this type this past weekend. She had a racing fork (no tabs) and even though the quick release mount was fastened very tight, it still managed to work itself loose while driving down the freeway.

Fortunately none of the cars behind the vehicle were hit and the bike didn't get run over so it was salvageable, but it could have been ugly.