1) G-Burgh is a full day trip...if not more. Rec you find a good book or historiography and read up before visiting....the knowledge will enhance the impact many times over. take in the Eternal Light Peace Memorial (more because of who else has been there) as well as the usual spots (e.g., Seminary Ridge, Soldiers National Cemetery, etc.)
2) If a theme vacation...visit National Cemetery and Robert E. Lee's home while in DC....Ford's Theatre as well.
3) I have friends who live in Philly and can get the drop on where to go if you change your mind.
Had a fantastic couple of days. Saw the Baltimore Harbor with the tall ships and the Blue Angels flying overhead. Spent a day in Gettysburg. What an amazingly reflective experience. War is hell and especially when fought among each other from the same country. Horrible!! I appreciate the suggestions. D.C. was great as well.