Tinker,
What kind of an SUV are you planning to get? My wife has a ML320 (similar in size to the MDX,RX300), and I think my GS300 has more room in the backseats. I'm 6'1 240, and when I have the seats back, my son's feet will touch the back of the seat. With the ML320, he does not fit. As for the trunk space, it is huge. I am able to fit two stollers, and a bunch of groceries. Plus, the rear doors open wide and allows more room to reach in to buckle up the youngsters. This is more difficult in a SUV, unless you are tall enough or nimble to get into the vehicle and buckle them up. OR unless you get something massive like a full size SUV. Good luck!