I need help planning a good cheap trip to washington dc for a weekend in July.?

I'm going to suggest the usual assortment of tourist spots downtown -- the White House (see the front and back! The front is better for taking photos - just cross the street, you can get a great shot with you and the White House from the little park there; the back is the more 'famous' view, but you're really far away), the Washington Monument, Lincoln Memorial, US Capitol, etc. Contact your congressperson (I think -- I'm Canadian!) to try and get a tour of the White House. (If you can't, check out the Visitors Center, which is kinda hidden on Pennsylvania Ave a block down or so.) Reserve tickets online in advance to get a tour of the Washington Monument - tickets are free, and reservations are a few bucks online. I'd recommend the Jefferson memorial too, but it's kinda out of the way. Depending what your kid's into, there's the Spy museum and the Air and Space museum that are both very cool and hands-on. And the Natural History museum has dinosaurs and that sort of thing. Oh! And the Zoo! It's surprisingly downtown, for a big zoo in a big city, and they have all sorts of animals, from lions and tigers and pandas and elephants down to little things like lizards and fish and spiders. Also, because it's a Smithsonian thing, it's free admission! It's Metro-able; just get off at "Zoo". Driving in DC is an absolute nightmare. Picture a city that was designed specifically to be confusing for invading armies, then factor in streets that change from being two-way to one-way depending on the time of day... If you don't have a GPS, don't even think about it -- park at the hotel, and take a cab/shuttle/public transportation in. Depending on your budget and what kind of a deal you can find, staying a little outside the main DC area and taking transportation in could be a cheaper option. Learn the Metro -- it's fairly straightforward, although I recommend carrying a map of it with you if you'll be using it a lot. (The Metro is the subway system, by the way.) It goes everywhere -- zoo, museums, the Mall, etc. as well as the 'suburbs', so to speak. They have day passes that allow unlimited rides, I believe. Watch for construction delays on the yellow and green lines downtown, though. DC is very walkable, especially in the denser tourist areas, so depending how mobile your kid(s) is/are, you might not need to use it much, but it's there when you do. Have a great trip!