As an employee of a U.S. Government agency, we must now book all our air travel through http://www.zegato.com. That website has got to be the most confusing site on the net, and it has taken me hours to make an airline reservation on it, and even then, our travel manager has notified me of errors I've made.
But the site requires me to be registered first with them by my agency, before I can make a reservation. All reservations go on a Government Travel Card, and are immediately transmitted to the travel manager where I work for review. So I can't start making personal airline reservations on it. I can easily see, though, which airlines offer what negotiated fares (YCA fares) between what points, and most all our way cheaper than any regular fares.
That said, as mentioned above, I make hotel reservations directly with hotels of my choosing, and I'll be reimbursed either what the hotel charges, or the maximum allowable per-diem rate for the location (whichever is less). Many hotels do offer "government rates," and I obviously do ask for them. As far as getting the government rate for personal travel, it is up to the hotel as to what they require. Some want to see official travel orders. Some others just want to see your employee ID card. Others won't give you the government rate unless it's on your government travel card. But there are hotels that will give you the rate just by seeing your government ID and will let you put the charge on a personal credit card. Whether you, as a government employee, would want to do that, or is even ethical, I can't say. But for me, to risk my agency finding out that I did that, and possibly even losing my job for it, is a risk I'm not going to take, even though it isn't likely my agency would find out.