In regards to buying new. My wife and I bought our first camper (new)10 years ago before kids. Everything we LOVED about it on the sales lot we HATED about it in the campground. I sold it and lost my butt. Point is we didn't really know what we wanted.
Now, we have small kids and "SprinklerMan" made a very good point. Kids are rough on stuff. We have an older camper that is paid for. Yes, I could go tomorrow and buy new, but not with two small wrecking balls running around. We camp at the beach a lot. Sand, sand and more sand gets tracked in. And if (when) something breaks I'm not that stressed about it as opposed to a brand new camper.
And the seasonal site.... Who cares!! Camping's camping !! When you fire up the grill and campfire and maybe even a cold one. Does it really matter where you are???