is a good place to look at tents and check features. They have a pretty good selection of very good tents.
Are you looking for something light-weight? Something that has tons of room? Something you're only going to take on car-camping trips?
If you are buying something that has to fit a bunch of people, and it doesn't matter if it'* a bit big, buy a cabin tent, one of the big square ones. They're easy to put up, have tons of usable floor space, and most people can stand up comfortably inside one.
If you plan on using the tent for smaller outings, as well, you may want to consider buying several smaller tents. That way you don't have to haul out a huge tent if you feel like going camping by yourself.
Take a look at how the poles are routed, the more places that poles cross each other, the harder the tent is going to be to pitch.
Whatever you end up buying, make sure it has a heavy-duty rain-fly, and make sure to use a ground cloth(heavy plastic sheeting works best, and it'* cheap.) Also pick up some Seam-Sealer and hit the seams with it. It will keep them from leaking.