There are many, many hotels in DC, most of which are only a short walk, cab ride or Metro ride from GWU. The following is a short list of the closet hotels/hostels to Lisner Auditorium.

George Washington University Inn
824 New Hampshire Avenue, NW
Washington, D.C. 20037
1-800-426-4455
(202) 337-6620
www.gwuinn.com

GWU's official hotel. Amenities include high-speed internet access in all rooms, valet parking.
[online reviews and info]

We have heard that GWU Inn is SOLD OUT.

Hotel Lombardy
2019 I Street, NW
Washington, D.C. 20006
1-800-424-5486
(202) 828-2600
www.hotellombardy.com

The Lombardy is an elegant but comfortable hotel with old-world, European hospitality, about one block from Lisner. Some may call it "quaint."
[online reviews and info]

$130-$259

sept 10-11 : Available
sept 12-13 : SOLD OUT

One Washington Circle
1 Washington Circle, NW
Washington, DC 20037
800.424.9671
www.thecirclehotel.com

All suite boutique hotel. Just a couple of blocks from Lisner at 23rd Street and Washington Circle.

Georgetown Suites
1111 30th Street NW
Washington, DC 20007
800.348.7203
www.georgetownsuites.com

Kings and queens, with kitchens in some suites. Some bedrooms can sleep up to six people. Limited availabilty.

$170 and up

Only a couple of rooms left.

The River Inn
924 25th Street NW
Washington, DC 20037
800.424.2741
www.theriverinn.com

Luxury suites in historic Foggy Bottom.

$199 – $269

About 15 rooms left, Sept 10-12.

St. Gregory Hotels and Suites
2033 M Street NW
Washington, DC
800.829.5034

Limited availability.

$279 for deluxe.

Sept 10-11 available. Sept 12 is SOLD OUT

Embassy Suites Hotel
1250 22nd Street, NW
Washington, D.C. 20037
1-800-362-2779
(202) 857-3388
www.embassysuites.com

Very nice full-service hotel, about 5 blocks from GWU.
[online reviews and info]

$180-$309

Ritz Carlton
1150 22nd St. NW
Washington, DC 20037
1-800-241-3333
(202) 835-0500
www.ritzcarlton.com

A top-notch hotel about 5 blocks from GWU.
[online reviews and info]

Expensive

Wyndham City Center Hotel
1143 New Hampshire Ave NW
Washington, D.C. 20037
1-800-778-7477
(202) 775-0800
www.wyndham.com

Another very nice full-service hotel, about 4 blocks from GWU. Very limited availability.

$279-$400

Highlander Motel
3336 Wilson Boulevard
Arlington, VA 22201
703.524.4300
www.highlandermotel.com

A no-frills but tidy motel (with parking) in Arlington. Close to both the Clarendon and Virginia Square metro stops, which are on the same Orange Metro line at GWU. Also within walking distance of Pho dinner restaurant, coffee shops, IOTA club. A cheaper option than DC proper!

$73

Allen Lee Hostel
2224 F St NW
Washington, DC 20037
1 - (800) 462-0186
(202) 331-1224
www.allenleehotel.com

More hostel listings in DC here

A youth hostel only a couple of blocks from GWU campus located in a large old building.
[online info]

$45-$58