Hi Connief84, welcome to the forum.
We visited Washington a few years back and stayed at the Holiday Inn Washington-Capitol/Smithsonian. Excellent location, it's one block from the Air and Space Museum ( we went there every single day ) and within walking distance of the Capitol and the (E'Enfant Plaza) Metro station. Bonus--because the sightseeing bus (Tourmobile) had an Air Museum stop, we were able to use the bus as a shuttle between the museums, monuments and our hotel; an all-day pass let you get off at any stop and re-board another bus at no charge.
Minus--Unfortunately there aren't a lot of restaurants around the Holiday Inn. I think there was a Mc Donald's but that's about it. The hotel's restaurants were kind of expensive
but, at the time, they were offering a 'kids eat free' deal. BTW, if you do stay at the Holiday Inn, do ask for a room away from the train line, perferably an inside room facing the courtyard, much quieter.
Hope this helps

Keep'em flying