lunch between baltimore and hershey, pa
In Hershey the Chocolate Avenue Grill has really good sandwiches.
Ditto for Isaac's:
The Soda Jerk is a fun bit of nostalgia:
I'm not as familiar with the downtown Harrisburg area, but one place we love to go is the Appalachian Brewing Company:
I assume you are taking 83 all the way to Harrisburg, then getting on 322 to Hershey and you are looking for some place en route?
If so, there are some decent places on Harrisburg's west shore such as Duke's, Dockside Willie's and Rockbass that all overlook the Susquehanna River.
Immediately after crossing the river, Passage to India is a fairly easy on/off from the highway if you like Indian food.
Closer to where you will pick up 322 is Lancaster Brewing Company, and the Capitol Diner is a pretty decent diner if you want something casual like that.
As you enter Hummelstown, we like the The Gas Station best, but the Warwick Hotel ("The Wick") is a good place for a burger and a beer.
I want to add that all the places mentioned above are great as well, but closer in to Hershey (except ABC). Soda Jerk and Isaac's are technically in Hummelstown like my last 2 mentions above.