Pre-wiring is always a nice way to help "future proof" your setup, if you have the option of doing that now. I would reccommend going with a 7.1 system, especially with two rows of seating. That way, you can hang the side surrounds directly parallel with the front seats (maybe slightly behind) and the rears will help fill out the back of the room for the back row.
In that set-up, I would go with all QS type speakers, no direct raidators since the back row might feel like they're a little removed from the soudn content with direct radiators. The spaciou feel of the rear-surround Qs will help to provide a nice "width" the back wall and they will blend better with the side QSs.
If you choose to go with direct radiators, you can always set them on a shelf, or use brackets of some sort to angle them towards the ceiling, using it as a reflective surface to disperse the direct radiating rear speakers. This will make the rear speakers appear as if they are coming from slightly further back in the room, also opening up the back wall.
Whatever you do, with two rows, you're going to have a lot of "sweet spot" to fill with non-localized, full sound. 7.1 seems like a perfect solution to this.
