RE: Gettysburg PA > Hoboken NJ
Well, if she is still in Gettysburg, there are a couple choices. The Texas Lunch (off the square) with Texas Style hot dogs and Texas Fries. The Lincon Diner, (off the square), haven't been there in ages but, remember it as being good. There is a restaurant that I can't remember the name of on the 'Y' diagonal from the Holiday Inn in the tourist area. Good food there too.
Further on Rt 30 in New Oxford (near Hanover PA) is the Cross Key's Diner. The original diner is either gone or hidden inside the new big building but they have a great menu with lots of choices.
Whats the rest of her route? Might have some other suggestions.