a buddy traded his matrix for a rav4. It's basically the same inside as a 5 seater, maybe a tidge larger. with the 7 seats in place you'll have almost no space for stuff.
We have a matrix as our day to day car. It's on the small side with two kids in baby seats and associated gear. So for road trips we take my crew cab truck. It's a real gas guzzler though at 14 mpg highway