We went through Lancaster last summer (beginning of August) enroute from Cherry Hill RV Parkin DC to Williamsport, PA to catch some of the Little League World Series. We have two boys who are 9 and 12 so decided to stop in Lancaster enroute to visit the Railway Museum and train ride, in Strasburg. The whole family loved our day at Strasburg. Cool little town. Amazing attraction. We stayed in Lancaster at the Old Mill Stream Campground. Lovely place. Nice spot on a creek. Would definitely stay there again.
From DC to Lancaster, PA which route to take has a lot to do with accidents and traffic on the day you travel. Pretty sure we took the 695 around Baltimore and then the 83 North to York and the 30 east to Lancaster and had no issues driving our 32 foot Class C on any of it.