Idk. We could do each place really.
Lancaster: Loxley's on Centerville Rd has a private room. Hoss's in Elizabethtown also has a private area, Bube's Brewery in Mt. Joy will also give you a private area. There's also Ruby Tuesday's at Rockvale Outlets that can cater to a larger group.
Harrisburg...hmmm...There's a Bob Evans off the Swatara exit of 283, There's an Applebees (I think) at Harrisburg East Mall. There's also a pretty decent Hibachi Grill and Buffet on Jonestown Rd. Along with an Olive Garden.