You're getting some good advice there^ How you plan to use the RV will make a big difference also. Are you planning on serious boondocking? Full hookup resorts? Electric or electric and water state parks? Daughters use a tent any while parked? Do you mind using public toilets and showers? With four people, I would look at adding serious square footage with as much slide as I could get. If you are planning on boondocking or won't use public facilities, you will want the largest tanks you can find. Be aware, there's not too many bunkhouse class A's out there, and trust me, you will want a bunkhouse. Setting up and breaking down the sleeper sofa every morning and night will get old quick. My wife and I have a class C for camping that's 33' bumper to bumper and it gets real small after a couple of weeks. We full time in a 40' fifth wheel, and we really wouldn't want anything smaller for full-time use. Even that gets to be unhandy after a couple of nights with our 6 year old granddaughter visiting. We have a 50 gallon black tank in the fiver, and we get about two weeks out of it before having to dump. The C has 35 gallon black tank, and we have to use the great outdoors or public facilities to go two weeks on it. We have full hookups on the fiver, so gray tanks aren't a problem. With the C, we have to really conserve water use because of the small gray tank when not in a full hookup site. Doubling the amount of people will cut that time in half.