There is a large selection of hotels available in Washington DC that should suit almost any budget, and one of the major considerations is location. It is a good idea to pick somewhere fairly central in order to be close to all the main attractions, as this will help you to avoid spending a fortune on public transport.
An excellent value if a little basic hotel that provides a great location right in the city centre is the 2* Best Western Capitol Skyline, which is right in the centre, just 5 blocks from the Capitol Building. The hotel is a great base for exploring the city.
For a hotel with a little more in the way of facilities you could try the 3* Washington Plaza hotel close to the White House. The hotel offers large rooms, some of which have great views, and the outdoor swimming pool is a great place to sit out in the sun during the hot summer.
If you are looking for a really high standard of accommodation where service is everything, and almost every conceivable facility is at your disposal, then the elegant 5* Sofitel on Lafayette Square is a great choice, and provides wonderful surroundings to relax in.