With the way you're asking it appears you're not PCSing, therefore lodging will not be "free".
www.Kayak.com search all the travel sites.
www.Hotwire.com will usually be your best deal, but you only get to select the basic area. If you choose a low star rating, you could be a rough area, generally speaking if you choose a 3 star rating or higher, you'd be in a safe area.