I rented an SUV from National in Sept.
I picked a red Chevy Blazer. That is the old style Blazer they didn't have any of the new Trailblazers at that time which is what I drive at home.
They also had those Buick SUV/Minivan things that Tiger Woods advertises and one other type. I think it was a Mitsubishi Montero.
You might want to call and ask if they have the larger SUVs, what I saw were all just the mid sized.
Or you might want to rent a mini van which would have more seating.