Gettysburg fanatic here. Go there many times a year.
Garyowen Irish Pub is really good. Hit this place frequently.
Pub & Restaraunt is also pretty good. Good burgers is what I get.
Pricy but good and a great old building is the a Dobbin House Tavern.
Now for a special night, Try the Cashtown Inn located in Cashtown , Pa. 15 minute ride of Gettysburg. This Place is very old, was the location of the confederate troops prior to the battle and makes almost everyone's top ghost tour. But I haven't seen any.
Hope you enjoy Gettysburg.