Are you there for just 1 day? Are you driving through, or staying?
Like I mentioned before, Knoebel's is 1 1/2 hours away - maybe up to 2 - from Hershey.
Knoebel's is very quaint.
I had to LOL at that. I was very upset when we pulled into the park. I looked at my wife and basically said "so we drove all this way to go to a county fair? The parking lot is a field!"
After a few rides it was all better.
For me, Twister was very rough. Not sure if it was the short sits or dividers, but it really seemed to beat me up in the rib and lower back (kidney) area. Still, I loved it and wished I had found it earlier in the day (instead of right before closing).
Hershey did seem to get less crowded in the evening. We ended the day at Midway America and managed to get on the 3 coasters will very little wait, while riding Lightning Racer several times each (alternating while watching the kids).
If you are able to get to Hershey the evening before, they had a free preview plan. Buy your tickets for the following day and depending on the time the park closes, you can get free admission for that night (usually about 2 1/2). I guess you still pay for parking for both days.
That would give you a chance to ride some of the coasters, go back the following day to hit the rest, and then leave early enough to make the trip to Knoebel's.
You'll enjoy either place. For the sheer number of coasters, it's Hershey. If you hit Knoebel's, also check out Fandango - fairly close to the Phoenix. Still not sure where Twister is - I found an employee that saw me running and was nice enough to give me a ride on his golf cart! I never would have made it there in time to ride it once, let alone 4 times!