I use Yakima SteelHead fork mounts to carry bikes on the roof of my MDX (see pictures in Yakima Roof Rack link in my signature).
While using the upright mount may be slightly more convenient because you do not have to remove the front wheel, I find fork mounts to be much more stable than the upright mounts. They are also easier to load on MDX roof since the bike is lighter with the front wheel removed.
I have been using Yakima SteelHead for the past 7+ years, and I never had any problems. I like them.
do a search using "bike rack" and Thule (I will try to link it below)and you will find a pretty good solution from Thule posted by cr (which I am probably going to purchase in the next few months). It uses the factory rack with Thule velo-vise (fork-mount) trays and an additional load bar for the front. While not a perfect solution, it's good and relatively easy with no permanent modifications. I have had velo-vise trays on my RAV4 for several years and really like them (easy to adjust, secure fit).Link to thread
I have been happy w/the Thule fork mount rack. It's not that difficult to get the bikes up there w/the doors opened, note the rack does add a bit more wind noise, esp. w/the sunroof open, but its not that bad. Just be careful going under overhangs!!