There are a couple of websites like
http://www.travelpets.com/ or
http://www.pettravel.com/
So far, when we travel to New Jersey, we've stayed in the Marriott's Residence Inn. The housekeepers put a magnet on the door to identify that we have a dog in the room just in case of fire. I believe that if you don't want anyone to go in the room while you are out, they would honor that. Unfortunately, we've never left Winston in the room by himself.