Washington: I'm working at a large consulting firm in the District and would like to relocate to Philadelphia or New York for personal reasons. Any thoughts on how to approach this topic with my boss? I would like to transfer to a different office and remain with the company, but I am uncertain as to the politics involved in such a move, and don't have any contacts in the other offices.
You don't have any contacts, but your boss might. Assuming you have a good relationship with your supervisor, approach him with exactly the same information you just gave me. You will need him as a reference, so you might as well involve him in the process from the beginning.
Arlington: I've been in the area for a few years now and I'm ready to move on. My biggest problem (aside from not knowing exactly what I want to do!) is that I don't know where I want to go next. I'm interested in both coasts and lots of places in between. What's the best way to get my resume out there so I don't miss an opportunity in a great place?
You don't need career advice, you need a really, really long road trip.
That said, if you want to guarantee that you won't find what you're looking for, try looking everywhere at once. You need to make some decisions and narrow down your preferences. Pick a career that interests you -- even if it feels somewhat random. Whittle down the list of places where you might be interested in moving, and visit them. Go where the two best intersect.