For the Kennedys, it's always been the chicks, in a convenient place away from the filth and stench of Boston.
As far as I can tell, the chance of hobnobbing with the Kennedys, in bed or possibly not, is the only reason that some people want to go there. There is a privacy aspect, since it's basically full of rich snobs plus the semi-normal people who keep the place up for them which are a rather closed community, and it is an island so access is limited, but unless you're actually trying to get in bed with a Kennedy (shudder - not the most attractive women around by a damn' sight) there really isn't anything to DO with all that privacy.