My Intruder measures 13' wide when set up not counting the awning, I'd want at least 20feet between sites, 30 would be nicer (I have been in a park where when both I and my next site neighbor had our slides out you had to zig-zag between us because, Well, both of our slides extended into the next site) LONG enough too, sixty feet, even the back in sites (Room to park a car in front) Pull through for the transients is nice.
Wide "roads" so you do not have to jink and job back and forth getting into a basck in site or worry about scraping a post or tree on a pull through, I've taken out a couple of site marker posts.
Good solid 50 amps. Too many parks there are too many sites on each chain (A chain is where you have a power distribution/meter box-----site----site---site---site
Many parks the cables are too small and the chains too long so by the time you get to the end the voltage is too low. Was talking to the electrician where I'm parked,
Now I belong to a pair of membership parks, This has nothing to do with what you are talking about but one of them, Great management, all the parks I have visited in that system had great managers INCLUDING the one where we zig-zaged between rigs (yes that was one of them) The other one Well the park I stay at in that system the most is just way too big, the result is the manager is run ragged and even with a large staff to assist they have very confusing policies and other issues and let's just say a few staffers are great,, The rest... Not so much. Other parks in that system are smaller, but still suffer from manager attitude issues.
Swimming pools, Tennis courts, Basketball courts, Put-Put golf (or real golf) and other thigns like that.. Nice but not necessary in my opinion.
A small but reasonable camp store.. Necessary items include sewer hoses, fresh water hoses, and the like, Soap (Laundry and dish) a few shancks (optional) and I'd like to see a SMALL inverntory of groceries (IE one gallon of milk, 2 loaves of bread) or else a "Shopping service" where one of the staffers can hit a local supermarket on the way into work tomorrow.. The supermarket would be responsible for putting up a web page where the customer can order, pay the staffer who then picks up the order and delivers the box the next morning.