I made the decision last weekend to go with the roof rack.
While it's gonna take a lot more energy to get the bikes up there (or a step ladder!), I couldn't get myself to sacrifice the convenience of being able to open the hatch unencumbered.
Also, you can leave the roof rack on there even when you're not using it, while a naked hitch rack looks plain silly.
Plus, if you're disaster-prone, there's probably a greater chance of some guy rear-ending you (and destroying the bike) than there is of you being careless enough to rip the bike off the top by driving into a parking garage...
At least I would hope!
