We have an Oztrail Tourer 10plus. It is huge. We bought for about $400 delivered, (ebay). It is very simple to put up, one pole in the middle, and a ridge pole at the back. Can fit at least 2 double matresses, plus a few singles. Only downside is it is a bit bulky, but if you take a trailer, boat or roof rack, should be no problem. Being canvas it is very comfy to sleep in. I don't have any photos but an internet search should find some pics. Good luck
Dimensions are 400cm x 305cm x 210cm High . Pics are here - http://www.sherryscamping.com.au/category70_1.htm
. If your boys are young the smaller versions on this page eg. Tourer 9, might be suited.