1) You want to time your trip to get to Gettysburg well after or well before July 1, 2 & 3 (or the closest weekend). Gettysburg is crowded all summer long but around the anniversary of the battle it is unbelievable.
2) If it must be over July 4 make your reservations ASAP. Many CG's are booked a year in advance.
3) If coming in from the west I would also avoid Rt. 30. "Interesting" is an understatement. Work your way over to Rt. 15 (maybe from I-80?) and head south on 15 to Gettysburg.
Good luck, safe travels & enjoy.
