I've compiled some suggested locations for conducting your next offsite meeting or workshop in the DC region. If you want more options, the website evenues.com has a more comprehensive list with hourly prices. 

Venue

Location

Comments

O Street Mansion

Washington, DC

Gaudy, quirky, over-the-top, and fun

National Museum of the American Indian

Washington, DC

Open, light-filled venue, centrally located

Hyatt Regency Capitol Hill

Washington, DC

Average urban hotel

National 4-H Youth Conference Center

Washington, DC

Very large, fairly basic

Hotel Palomar

Washington, DC

Average urban hotel

Nationals Stadium

Washington, DC

Lots of cool spaces, but not on game nights (duh)

Penn Social

Washington, DC

Bar with huge basement meeting room

Hill Center

Washington, DC

Historic location, light-filled rooms

Eastern Market North Hall

Washington, DC

Large, high ceilinged meeting room

Aspen Wye River Conference Center

Queenstown, MD

Rustic setting, comfortable rooms, indoor and outdoor meeting spaces

Ramada Conference Center

Edgewood, MD

Dumpy

Country Inn and Suites

Bel Aire, MD

Dumpy

Mt. Washington Conference Center

Baltimore, MD

Very nice retreat venue

Gaithersburg Holiday Inn

Gaithersburg, MD

New

Best Western Hotel

Rockville, MD

Dumpy

Bethesda North Marriott Conference Center

Bethesda, MD

Very deluxe feeling

B’nai Israel Congregation

Rockville, MD

Large, light-filled conference room

Doubletree Hotel Dulles

Sterling, VA

Smallish rooms, but otherwise a standard exurban hotel

Hyatt Regency Crystal City

Crystal City, VA

Standard hotel space

Hyatt Fair Lakes

Fairfax, VA

Perfectly nice exurban hotel

Washington Dulles Hilton

Herndon, VA

Nice exurban hotel

Landsdowne Resort

Leesburg, VA

Expensive, high-end conference center

Point of View Retreat

Lorton, VA

Rustic setting, comfortable rooms

Tysons-Pimmit Regional Library

Falls Church, VA

Basic space, a little dog-eared. (NGOs only)

Dolley Madison Regional Library

McLean, VA

Open, light-filled, modern spaces. (NGOs only)

Great Falls Regional Library

Great Falls, VA

Large room, easy to reconfigure (NGOs only)