There are other CG's in the area but if your going to Hershey Park staying at the Hershey Park CG is the way to go.That is assuming you plan to visit the amusement Park.
If you stay off site you will have to drive and park at the amusement park. Just the time and cost involved in parking and using trams to get into park outweigh any other advantage you may get from staying outside the park vs. at the park.
I have stayed at Hershey Conewago and Elizabethtown. Both are decent places but they are relatively tight as well in terms of site size.
At the end of the day the Hershey Park CG is your best bet for enjoying a weekend at the amusement park.