I always reference the hotel finder at http://www.dogfriendly.com/. You search by state and then drill down into the various cities and towns -- at the lowest level you will find a list of hotels that accept dogs (and pets in general). I have found them to be pretty comprehensive. They also reference what chains have chain-wide policies or at least take pets in a majority of properties (La Quinta, Motel 6). The site also has lots of other useful information too (i.e. what restaurants you can take your dog with you while on vacation).