I'd certainly buy a tent for more people than plan to use it. If you choose airbeds, you'll only get four in a sixth berth tent. Also, there are times when the weather isn't great so you need enough room to sit around a table, reading, playing games. Also, we usually end up with a pile of outdoor toys and you'll need somewhere for a clothes bag.
We have a Vango Lomond 600, about three years old now. The canopy is very handy for giving a bit of shade (there are times when you'll need it), we also leave our coolbag outside, a couple of other bits of equipment under it, (or boots in your case). Very happy with it.
We started camping with the basics, and slowly built up when we knew what we needed. Getting those extra things in time does make it more enjoyable though, eg outdoor toys for the kids, good size table for eating out, preparing food, blankets are handy for chilly evenings.
Either way, hope you enjoy it. We have a camping trip booked in July, I don't care what else I miss out on this year (even our holiday abroad at Easter), but I think we'll both be disappointed if we can go camping!