Whatever you get, remember that your children are growing quickly. Be sure that the bunks will accommodate adult sized people, as some 12 year olds, (mine) will be over 5'8" and 140#. Many of the bunk houses I've seen recently have a short bed that can only hold 100 pounds.
Also, another big factor to consider is length of the trailer. Will you be parking it at one site the entire summer? Will you go to state parks? Longer trailers make finding a site more difficult.
One last word of advise is to consider finding a bunkhouse with a door to the kids room if you have children that still nap. I found it invaluable to be able to close the bunkhouse door during nap or early bedtime. The rest of the family could cook, use the bathroom, etc, and the toddler didn't have her sleep interrupted. Priceless.
