We tent camp (oztent and tagalong) but also take a Oztrail Deluxe Gazebo 3x3m for longer stays. The tent does give us a biggish central room, but the gazebo extends it out which is good for wet weather. We also have the side walls 2xsolid, 2x fly mesh. Securing it in windy weather is the hardest part - extra pegs and ropes are a must.
I don't find the walls a hassle to put up. Its a couple of zips and clips and they're done. We usually use one or two as a sunshade/windbreak anyway and just roll them up when not required
Because we don't have a trailer, with our kids we limit them to medium duffle bag for clothes and one shared small backpack for toys. They're pretty good at going off and making their own fun - a stick will become a gun, sword, a horse and effective brother beater. Rocks become pets with a little bit of permanent marker, or cars, or UFO's, etc etc.
If you have more space you just tend to fill it. We go camping with another family and its insane what they bring - takes them a day just to pack the ute- 3xscooters, 3xbikes, 3 different types of nerf guns each, Lightsabers, ninja swords, Star wars toys & the list goes on. And half the time they're never used. I just couldn't do it.