E.S.
Hi-
We love camping too! We started with our first son was 6 months have camped frequently (3-4 times a year) since then. We bought an 8 person tent for our family of four (as the other reviewer noted, the person count is about as accurate as the MPG advertisements on new cars).
The most important thing for us was ease of putting up the humongous tent. With one parent corralling the young-uns, that leaves one parent to put up tent. And, parent has to do the tent quick, b/c kids are all ansty having been cooped up for hours on the drive up. You're lucky b/c you might be able to get 14yo to help.
So, I'm coming to the reason I splurged and bought the Northface Trailhead 8 ($400 REI). Husband can put it up by himself in about 15min, and the thing is quality. Some of our friend's cheapo tents last one outing, then the zippers break, poles snap, and are generally worth what you pay for.
Best of luck in your decision!