Couple notes about DC area. At all cost, avoid I-95 during rush hours 6:30-9 am and 3:30-6:30 pm, it can be brutal.
Strongly recommend against grabbing a snack at the food trucks in DC. The museums are awesome so take your time going through them.
Spring is a terrific time to go; summers can be extremely hot and humid.
Tried to answer your PM but for some reason they're not going through.
My suggestion would be the Klamath/Crescent City area (better cell and shopping in Crescent City but not as pretty as Klamath).