We usually stay at the JW Marriott but have recently stayed at the Fairfield Inn & Suites on H Street. The metro is a block away. It's in Chinatown and is easy for access anywhere. You are also 8-10 blocks up from Pennsylvania Ave with the Newseum right there. It includes breakfast and is usually reasonably priced. It was previously the Red Roof Inn but that closed and Marriott bought and completely renovated the hotel. Hope this helps.
I used Priceline and won the Renaissance Washington, DC Dupont Circle Hotel in May. We enjoyed it and it was very easy to get to the Metro from there. Also spent a couple nights at the Savoy Suites...little further away, and while they had shuttle service to a nearby Metro station it wasn't quite as convenient.
I have been able to get good deals on the Embassy Suites in the area. With a full breakfast and comfortable accommodations for a family, I consider the deals I've gotten "well priced" -- but they aren't bargain basement low.
We're going to DC in a few weeks, and I was able to get a great rate booking through wdcahotels.com. We'll be staying at the Residence Inn Washington DC/ Capitol. I haven't stayed there before, but it gets good reviews, it's close to a metro stop, and walking distance to the National Mall. Plus it has free breakfast and the rooms all have kitchenettes (it's so nice not to have to eat out for every single meal with kids). The rate was much less than what was showing on marriott's own website.