OK... unless Larry suggest another place:
I just did a quick search...
Lancaster Brewing Company
302 North Plum Street Lancaster, PA 17602
Seems like they have good, fairly priced food.... although I won't be drinking since we're riding.
If you would rather just go to a good diner... it sounds like Neptune diner is the spot:
924 North Prince Street Lancaster, PA 17603
I'm leaving now (I'm about 1:15 - 1:30 away from lancaster). I'll head towards the brewing company place, but I'll check the forums to see if you'd rather hit the diner