I have considered it. I've also considered writing a few history books, though that's generally easier to do if you have PhD in history. My suspicion is that I'll just continue reading books on the subject, and partaking of history lectures, but who knows for sure.
W&M does have a great program. I believe that Karin Wulf is a professor in their program, and she's a historian that I do follow.
@Tom McAndrew, here's my (perhaps insufficiently informed) take:
A PhD should be a means to an end, not an end in itself. The only real benefit in you getting a PhD would be that you would be interacting with a whole bunch of young, talented, driven people who are absolutely gaga about history and would like nothing better than to talk to you about it. You probably already experience this, as you "partake in history lectures." The historians I know from my university, with one exception, noted below, the topics of their dissertation research are extremely narrow (for example, public education in France between the world wars). I suspect that your field of concentration, the Revolutionary War, has been done to death.
In typing this, it occurred to me that I'm not saying anything you don't already know and haven't already considered. I'll go ahead and post so as to educate anyone who might not be up to speed on this.
The one exception is the late Anne Butler, who wrote about prostitution in the American West. Damn, a great topic and she wrote a very fine book about this.
It's nice to have the prestige of a PhD and be able to make small talk in cocktail parties about mathematics or history. People at my gym are usually amazed to find that I have a PhD in mathematics (I'm usually one of the very few deaf people they know, which is part of it), and that's nice, good for a smile. But, really, they are much more impressed when I tell them that I graduated Neshaminy; some have fainted dead away when I've told them this. I've learned to keep this to myself, just as I wouldn't tell them I'd won the lottery.