Budget
Carriage House
Capitol Hill is full of lovely old residences, and this provides a nice opportunity to stay in one. It is furnished with antiques, has WiFi, separate coach house, central courtyard, and an uninspired continental breakfast.
Maison Orleans B&B
A little B&B with three rooms in a beautiful old rowhouse. Friendly and knowledgeable owner, small garden in the back, WiFi, continental breakfast.
Midrange
Capitol Hill Suites
This is a fine, undistinguished but for the location option for extended stay on Capitol Hill. If you just want to get out of the sun for a second and rest your bones, the lobby is quite comfy.
Liaison Hotel
A boutique hotel between Union Station and the Capitol, whose rooftop pool only open during warm months has a fantastic view.
Hotel George Washington
A trendy boutique with airy rooms and a French restaurant next to Union Station.
Top end
Hyatt Regency Washington on Capitol Hill
The hotel occupies a full city block in the heart of Capitol Hill, between the Capitol and Union Station, and has a lovely, large, plant-filled atrium. Avoid the absurdly overpriced hotel restaurant, unless you're in the mood for a $10 bowl cornflakes.
Phoenix Park Hotel
Hotel of the Irish! Rooms are furnished in an eighteenth century Irish Manor style, Irish entertainers are at the Dubliner bar, and it's also right next to Union Station.
A small hotel or B&B on the Hill is a great choice for a stay in D.C., and one that is usually overlooked. It's a great neighborhood for walking, has a fine nightlife and dining scene, and is well-served by Metro.