If staying with family locally isn't an option, there are a variety of lodging options in Los Alamos, White Rock and down in the valley. 

Prices include tax (except for Hilltop House) and are for two adults for two nights.  Hotels are listed from cheapest to most expensive.

Motel 6 Ashley Inn
2175 Trinity Drive
Los Alamos, NM 87544
(505) 662-7211
Rooms from $101.98 for August 3 - 5
http://www.ashleyinnlosalamos.com/

North Road Inn
2127 North Road
Los Alamos, NM 87544-3020
(505) 662-3678
Rooms from $158 for August 3 - 5
http://www.northroadinn.com/Site/NORTH_ROAD_INN.html

Best Western Hilltop House
400 Trinity Drive
Los Alamos, NM
(505) 662-2441
Rooms from $150(+tax) for August 3 - 5
http://book.bestwestern.com/bestwestern/US/NM/Los-Alamos-hotels/BEST-WESTERN-Hilltop-House-Hotel/Hotel-Overview.do?propertyCode=32099&cm_mmc=PTI-_-local-_-feed-_-32099

Comfort Inn & Suites (Formerly the Holiday Inn Express)
2455 Trinity Drive
Los Alamos, NM 87544
(505) 661-1110
Rooms from $179.52 for August 3 - 5
http://www.comfortinn.com/hotel-los_alamos-new_mexico-NM152

Adobe Pines Bed & Breakfast
2455 Trinity Drive
Los Alamos, NM
(505) 661-1110
Rooms from $211.15 for August 3 - 5
http://www.losalamoslodging.com/

The Canyon Inn
80 Canyon Road
Los Alamos, NM
(505) 662-9595
Rooms from $217.89 for August 3 - 5
http://www.canyoninnbnb.com/

Cities of Gold Casino Hotel
10-B Cities of Gold Road
Santa Fe, NM 87506
1-877-455-0515
1-505-455-0515
Rooms from $225.79 for August 3 - 5
http://www.citiesofgold.com/lodging#contact

Hampton Inn
124 State Highway 4
White Rock, NM
(505) 672-3838
Rooms from $230 for August 3 - 5
http://www.hamptoninn.com/en/hp/hotels/index.jhtml?ctyhocn=LAMNMHX

Buffalo Thunder Hilton Resort
20 Buffalo Thunder Trail
Santa Fe, New Mexico 87506
1-505-455-5555
Rooms from $423.36 for August 3 - 5
http://www.buffalothunderresort.com/santa-fe-lodging/index.cfm