The great thing about this hobby is the diversity of rigs and the way we use them. No one is right or wrong, what they decide is what is right for them and maybe only them.
We like to find a new spot every time but I wouldn't mind having something set up closer for those short weekends. So much time is spent in travel and set up that it's only worth doing if we have at least four days or more.
New vs used...We looked at a lot of used first and found them dirty, smelly and needing repairs. Even if I do own a cleaning and repair service, I wanted to go camping not spend months cleaning and rebuilding. There may be perfect units out there but we didn't see them.
As gar as depreciation goes we bought a inexpensive entry level unit and would have taken a hit if we traded it in right away. Then again we got a great price on a year end deal and used they are running within a grand or two of what we paid for the same year. We also knew we would have a warranty for at least the first year on most things and the roof much longer.
I do think it is a good idea to visit the camp ground you pick a few times, especially on a busy holiday weekend to see what it is like. Talk to your potential neighbors, the management, maybe they will have a rental you can try out first. Getting a campground you don't like for a weekend is one thing, a full season is another.
Once set up I think you will have a great time. As a kid our family had both a cabin and a trailer and us kids loved them both. After the folks sold the cabin we primarily used one campground and we were never bored. we were camping.