We were just at hershey high meadow this passed weekend. We had a site right on the upper playground. Yes there are trains, more like every hour or so, but just the diesel sound and clacking, not too loud. I slept perfectly fine, DW on the other hand, she can hear a fly cough in the basement. I found the cg to be nice, and the kids have fun. We live in Harrisburg so we didn't travel out to do anything else. It seems that most everything has been mentioned, although don't forget about the "farm show complex" they always have stuff going on!
Enjoy your visit!