Welcome Dogdog and congratulations (ok a little early but you've been pre-congratulated LOL).
You're going to get all kinds of answers to that question. How are you leaning? Do you want to cover it?
Personally we cover our RV but its parked in a storage lot next to a bunch of other RVs which keeps the wind sort of down (as opposed to it sitting out in the middle of a field with nothing protecting it from the wind).
The pros: Keeps the sun off the outside (and inside), keeps the dirt out. (We've had our unit 4 seasons now and have kept it covered for 6 months of the year--yeah winter--the finish still looks pretty good. Yeah I also wash and protect it in the spring).
Some cons: If it doesn't fit tight enough it may rub on the sides leaving marks, if you live in a warmer climate it may hold moisture in, and sometimes the little critters are even more emboldened under a cover.