The 1500 loop is a partial loop for tent campers/popups and since you have a Class A, it wouldn't be practical - no sewer. The 1600 loop is a full hookup site and is the closest full hookup loop located near the pool but quite a ways from the Marina.
I would recommend staying in a preferred loop since it's close to the marina, trading post and Trails End. Those loops would be the 100-300. Personally I don't think the premium loops are worth the extra $10 a night or $15 more than a full hookup site. Plus you could get a premium site and be at the farthest point from the Marina (if they put you in the 1100, 1200 or 1300 loops).