I think a trailer is a great choice. As others have stated, you will not save money using an RV. I have done a lot of calculations and I only saved money with the RV on one trip. However, I would not give up the experience for anything. I want to sleep in my own bed and be able to cook my own meals. You can also park in places where there is no hotel.
As far as what to purchase, you want to take the dry weight of the trailer and add about 1000 pounds for your stuff. You need to add the weight of your and your kids and gear in the truck. You do not want the total weight to be close to the weight limit the truck can pull. You want a little breathing room. We purchased a trailer and we were close to the limit. It worked but the truck had to work hard out west going up and down hills. We moved to a diesel that could pull more weight and things were much easier.
