That is kind of a loaded question, since everyone has the own preferances, but since you want W/E/S, then you will need a preferred or full site. The Premium sites are an upcharge because they have more concrete to accomodate larger rigs, but you can put whatever you want on that site. All the sites are level, so that is not a problem.
This is the map of the Fort.
http://allears.net/acc/fortwmap1.jpg
This is a list of the sites:
Loop 100 - Preferred
Loop 200 - Preferred
Loop 300 - Preferred (Pet friendly loop)
Loop 400 - Premium (Pet friendly loop)
Loop 500 - Premium (Pet friendly loop)
Loop 600 - Premium (Pet friendly loop)
Loop 700 - Premium (Pet friendly loop)
Loop 800 - Premium (Pet friendly loop)
Loop 900 - Premium (Pet friendly loop)
Loop 1000 - Premium
Loop 1100 - Premium
Loop 1200 - Premium
Loop 1300 - Premium
Loop 1400 - Premium
Loop 1500 - Partial
Loop 1600 - Full (Pet friendly loop)
Loop 1700 - Full (Pet friendly loop)
Loop 1800 - Full (Pet friendly loop)
Loop 1900 - Full (Pet friendly loop)
Loop 2000 - Partial
Personally, I am a fan of the 100 loop. It is a short loop, so it is a short walk to the comfort station, an easy walk to the lake & boat landing and you are close to Trail's End, etc. But you are further away from the pool & campfire program.