I wanted a lot of flexiblity with my roof rack on my '07 GC, so I removed the factory crossbars, and put on Thule Aero bars, the six pair ski rack and two V2 bike trays. This set up also allows me to easily install my Thule Cascade 1600 cargo box without removing the bike trays. I've been a big fan of Thule stuff for years, despite the steep price, and I really like the way this setup works on my GC.
I originally did not install the fairing, but experienced a low whistle and occasional deep rumble on the highway without it. After installing the fairing, the whole set up as you see it is, without exaggeration, quieter than it was with just the factory cross bars!
Link to pic below