I have a 2002 E350 w/ v10. They are great tow vehicles. You have one of the few to come with factory 4.10's which are better for towing. Most, including mine came with 3.73. From a tow vehicle perspective you have the capacity to get most travel trailers they make.
I would be looking for a quad bunkhouse so everyone has there own bed. These are commonly called out as 29 - 32' campers. They will measure 31' to about 36' long from ball to bumper.
Clothes storage in them runs from minimal to extensive so keep that in mind when looking.
Will you be camping with full hook-ups? If not then pay attention to water capacity. Ultra-lights will start at 30 gallons. Others will hold 40 - 50 gallons. Some of the newer Jayco's will hold 86 gallons but most anything else will top out around 50.
With teenage boys pay attention to bunk sizes to make sure everyone fits. 74" long is typical but some are shorter. Some bunks are as narrow as 26" and some are wider. Quad bunk houses many times have wider bunks on one side than the other.