Before even shopping for a vehicle there are things to be considered. Will the unit be used for just living or will you be living in it for weeks at a time? Do you want to tow a car too? How big do you want it or will you be comfortable driving? How many people will sleep in it?
Towing a car - There are 2 ways to tow the car. A full trailer is one you drive onto and all 4 tires are off the ground. They are typically 16' ish long which adds that many more feet to the RV. A dolly is just 2 wheels on a hitch that the front tires rest on. The back tires are on the road and will rotate and add miles to the odometer. They are a lot shorter.
We have learned this the hard way. Our car is all wheel drive and can not be towed so it would have to go onto a trailer. With a 34' long Bounder by Fleetwood and a 16' trailer we would be 50' long no matter where we went. For our 1st venture with the RV we decided that was too long and that we should use the dolly. Trouble with that was we needed to get another car, to tow. lol
So knowing what you want to use it for and if you will be towing a car to get around in, is the 2nd decision to make after it is decided you want to try the RV life. We opted for a larger one because we will continue our eBay business (http://stores.ebay.com/Herbs-Crafts-Gifts) on the road and need the storage.
Beds - Typically there is a bedroom. Class C also has the bunk up and over the drivers seat. The Class A has a 2 benches on either side of the table that break down into a bunk. Depending on size, the couch pulls out to a full bed too.
Shower - There is the shower in the tub like at home or the whole bathroom becomes the shower with the drain in the floor. We do not have any experience with either so have no opinion. Ours is in the tub.
Refrigerator / Freezer - Size is important if you are going to be out for several days at a time. Newer ones have ice makers.
Stove / Oven - I am reading that a lot of folks use little BBQ grills rather than using the stove. The oven looks small too and another preference they talk about is using a toaster oven. We found an Oster 6 slice toaster oven / convection oven for less than $75.00. I love the idea of it all being in one and once we are plugged in, the electricity to use it will not put time on the generator. (Besides who wants to clean a tiny little, dark oven?!)
TV - With the changes coming from analog TV a lot of folks are using a satellite dish. We have Direct TV because we have been told they are more user friendly. All we have to do is take the DVR receiver from the house, plug it in and adjust the dish based on the zip code where we are.
These are some of the basic options but many, many to consider like full awning to make a patio- like area, awnings on the outside over the little windows; window blinds; fans (can they stay open while traveling?); air conditioning - do they both run at the same time?; water filter; clean water tank size; water filter unit?; lights in the compartments where the clean outs are?; outside faucet to rinse off from the beach or to clean all those fish that are going to be caught?; and so many, many more.
Make a list of what is important to have and what would be nice to have and then go shopping. We had no clue but were very lucky to find the one we did. Thank you Dick @ Pikes Peak Travel Center in Colorado Springs, CO.