I love 1500. Have stayed there 3 years in a row. The closeness to all amenities is great.
The only thing about 1500, however is the "sand pad" portion of most of the sites seems to be smaller overall than 2000.
2000 looks to be a newer loop and as such, the sand pads are all designed a little differently and seem to be set up better for tent campers.
Also, since loop 2000 is so huge there is a good possibility you will be a good distance from a comfort station.
One other disadvantage to Loop 2000 is it is on the purple bus line which DOES NOT stop anywhere near the Meadows trading post area. You will either need to walk or ride bikes/golf cart, or take a bus to outpost or settlement, then transfer to get to the Movie/Campfire, Bike Barn, etc.
Set up your stuff in the backyard (or other campsite) similar to how you believe it would be set up at Ft. Wilderness, then measure the width and length of your stuff. Then tell Central Reservtions the minimum dimensions of the pad you will need. Also once you arrive, if you don't like the site you've been assigned, feel free to drive around the Loop to see if there are any other sites that you like better that are empty. Then call the front desk from a house phone and most likely they will allow you to move.
Carol