We just got our 1st RV went with a class C. We have 5 kids and a St Bernard. We went on the 1st trip to Hershey this summer and it was great, all of the kids loved it, even our 16 yr old daughter loved it. It may have been our best trip to Hershey yet! Kids don't even seem to care if the RV leaves the driveway. They are happy camping right where it is now!
When we would go on vacation we would need 2 hotel rooms, plus
all of the food we had to buy. Vacations were short and expensive. We also dabled in renting condos and such but we didn't like that much.
We are taking our 1st trip to Disney this summer

and we are camping. When we checked the costs on all our options, the purchase of the RV and vacationing in it was well better then the others.
We love going to Virginia and try going every two years (may change after a trip to WDW). We used VA to compare our cost and it was almost 1/2 the cost in an RV!
I would recomend (based on my limited experience) that you go used before you put in the big $$ on a new RV. We got ourselves a 2002 Class C Coachman with all the options and 54k miles.
We took about 2 years to figure out what we wanted and to be sure it was for us. Slowly eliminated types of RV based on costs and needs.
We even considered gas prices but, with the RV is only get about 2-3 miles less per gallon then the conversion van we have.
As a PP said, don't let any salesman presure you into anything. I almost fell for it, the hint that something was wrong was when he refused to allow me to have an outside service tech look over the rig. Turns out there was a lot of potential damage from their failure to winterize (with full tanks). Found all of the tanks were big blocks of ice.
Also get out and see the shows, look through all of the rigs, sit down relax and see if you like them...bring the kids along once or twice too and see what they like about it.
Good luck!