I had a friend who had a roof rack on top of a Durango. He took his and his wife's bikes on a family vacation to a lkae about a four hour drive from home. Coming home, after the long drive and being in the car with the kids for 4 hours, he pulled the car into the garage. Oooops!! Out of sight, out of mind. Result = Damaged house, destroyed the bikes, and damaged the roof of the Durango. Fortunately the bikes were entry-level comfort bikes (I think they were low-end Treks) and his homeowners insurance covered most of the damage to the house and car, and paid replacement cost for the bikes.

I have a hitch-mount rack and it works great (can't think of the model). It is the kind that the bikes hang from, versus one that has a platform the bikes sit on (which is probably preferred).