DW and I are also planning a trip up the east coast as far as Nova Scotia, so we will be following this thread with interest. As to time, we are thinking after labor day ought to be good, although we may need to start out (from Arkansas) in late August. Definitely want to be in New Hampshire/Vermont during last week of September.
Have only a vague idea of trip now, but in South Caroline: Charleston: yes; Myrtle Beach: avoid.
North Carolina: have already done Blue Ridge Parkway (a must-see), so was thinking of driving the Outer Banks. Don't know anything about it, but sounds interesting.
Virginia: Will do Williamsburg (a must-see) again. Would like to take the tunnel up to Delaware. DW loves historical places. Have already spent much time in Washington, D.C. so won't visit it this time.
Philadelphia: Art Museum and historic districts. Have no idea where we are going to camp.
New York: give a wide birth. Have been there several times by plane, train, and Liberty Harbor. Not for this trip.
Rhode Island: See how the swells live at Newport, if they will allow anyone in a Ford F350 pickup to even enter.
Still looking at New England, New Brunswick, and Nova Scotia.