we have roof mounts for our bikes on DH's car. I am the same size as you
and am able to life my bike up there and take it down. I can't do the tandem it's too heavy. I would prefer a rear rack, although I watched as two women backed into each other and crunched their bikes/racks in a park near her.
On the other hand, too many of my friends have driven into parking garages and other low places and injured seriously expensive bikes on top of the car.
It is a hassle to put my bike into my car, but once it's in (if i don't snag cables and lose bar ends) it's safe and dry.