If you want to take some further trips, look into Longwood Gardens, which is absolutely amazing.

I saw Aviation mentioned, you may want to check out the Piper Museum in Lock Haven, particularly for a schedule of fly-in events.

Find a cave or two to explore. Penn's Cave is a boat tour, but there are others that are fun walking tours. Also consider a coal mine tour if history is interesting to you.

I second looking into Harrisburg Univ concert schedule, they have a bit of everything and year-round as well. I'd say most attendees aren't even college aged at most of the shows.

Carlisle area has a ton of car-related events and museums. I'm not even "into" cars but I enjoyed that a lot.