Mini-Vacation

It's been awhile since we've taken a real vacation. We've had a few short trips (mostly to visit family, or a few extra days tacked on to an out-of-town wedding or a business trip), but it's been a couple of years since we really splurged on a nice vacation. We've got a lengthy list of potential destinations, but until the credit cards are fully paid off it's too hard to justify spending the money. 

We recently decided that we're going to take another mini-vacation, to the nation's capital. It'll only be for a few days, and we're going to do it as cheaply as possible. 

We can drive there for about $100 in fuel (not counting wear & tear on the vehicle), and I haven't been able to find plane or train tickets for anywhere near that low. Low-end hotels in the DC-area are running about $75/night, which would add a pretty significant cost to the trip. Instead, we've decided to hit up a few friends/family members who live nearby and see if any of them are willing to give up their couch to us. I think we'll offer to buy dinner in exchange, but it should still be FAR cheaper than a hotel would. We'll need to pay for parking while we're there, and we'll likely also buy some transit passes to get around town. 

Fortunately, it looks like a lot of the attractions are free, so the only real expense while we're there will be food.

I definitely want to check out the White House and some of the national museums, anyone know of other free places around DC to visit?