Hey funnyfarm,
Check out the OzTents before you buy - sounds simple, but I really wanted one until I actually spent half an hour with one. Being 6"6+, they were too small - I couldn't stand up inside one. Which really counted it out for me. I couldn't believe that something so long you had to put it on your roofracks wouldn't have enough space for me! Granted, my requirements aren't exactly mainstream, but I'm certain that everyone has their own particular quirks you need to look out for.
That said, I think you've got a reasonably firm handle on your decision. There's pros and cons either way. We have just spent Easter up at Pinnacle Village, and half the campsite was camper trailers, and the other half was fishing boats and tents with tarps. We were feeling sorry for them having to be huddled under their dodgy tarps with their falling over tents while we had nice big camper trailers with fancy kitchens. They were no-doubt sitting under their tarps feeling sorry for us, that we didn't have any boats to head out on the reef with, and were stuck on dry land all day
. Horses for courses.
Personally, with kids, I don't think you can go past the convenience of a quick setup camper trailer, but that's just my preference. I'm a big fan of tents, and have always had quick setup touring tents in the past, but still reckon I can have our softfloor camper set up quicker than the old tent + awning/tarp. A cheap offroad trailer + an OzTrail (or locally made) camper top would be an inexpensive way to get a great setup that you can extend with a basic kitchen/water tank/battery setup, without breaking the bank. Keeps the $$$s freed up for your other needs, but still gives you an easy-to-use, integrated camping system that's quick and simple.
If you've got the trailer anyway...
Good luck!
Matto