I haver a Saris Bones, and I like it. I put a sock over the part that sits on the trunk top so it won't damage the paint (stole that idea from a BMW that had a bike rack on the trunk). I like it. We've taken our bikes on thousand mile road trips and have had no problems. When the wind is gusty, the bikes move around a little on the back (they sway a little on the highway, but we lock them on with a long bike lock so they're on there tight).
The way the Saris sits, you can have access to the trunk at all times. I keep mine on there all the time- just makes the trunk heavier (and be careful or you'll hit your head with the rack when lowering the trunk lid if you forget it's on there ).
Roof racks are too tall for me, and I refuse to carry a footstool to get my bike down (far too much trouble). Trailer hitch just wasn't a consideration either. The trunk rack works great for us!