Newbie - Class C Motor/Brand questions...

There is a direct correlation in the length of the RV and the Occupant and Cargo Carrying Capacity (OCCC) of the rig. In general, the longer the RV the less weight of people and stuff it can carry. The OP has noted that they will be carrying four people in most cases and possibly more at times with the extended family. Remember in most Class C and some Class A motorhomes, it is not the space you have available, but rather the weight that the chassis has available to carry things (including people). Options like leveling systems and slideouts add weight and decrease OCCC.

If buying used, check the date codes on the tires. Suggest that you by new tires if older than 6 years. Make sure all appliances work.

Good luck and have fun.