I'm taking my two daughters to Washington DC this weekend, and we plan on keeping the cost of the trip as low as possible. In fact, I'm surprised at how cheap it will be for us to go. I thought I'd share my discoveries, so that others who may be thinking that a trip to DC isn't affordable will see that it actually is.
There isn't any way of getting out of paying for gas to get to Washington DC, but there are commuter parking lots available if you simply want to visit DC for a day. As for hotels, you have a choice. A few of my friends stay just outside of DC where the room rates are cheap. They make sure the hotel is near a subway station for easy access to the DC sites. I prefer to spend the money that would be spent on the subway on a hotel room within DC that is in walking distance to all of the attractions. I got an excellent rate by booking ahead and taking the no-refund rate. It's risky, but saved me over $200. The hotel also had an enormous free breakfast each morning and a microwave and refrigerator directly in the guest room. I'm bringing my own food.