My first input is, buy bigger than you want to buy, but no bigger than you can safely tow. You have three kids, and I assume they are fairly young (NOW). They will need places to store they stuff (as will you) and one thing you give up with bunk houses is storage space.
We bought a 31 ft MH with bunks. One for the grand nephew which has only been used thrice, and a place to house the pets and their stuff. We found there is very little (nil comes to mind) room for anything the kid needs to take.
A lot to think about.
