This topic was covered during our ethics training. Essentially, you can use the government rate on leisure travel but cannot misrepresent that you are on government travel if asked. I've encountered a few occasions (peak season San Diego marriott hotels) in which the hotel terms and conditions stated that the rate is not available for government leisure travel. That doesn't occur often, though. At most hyatts, I have been asked for an ID or they just use the government credit card as ID.