I just knocked $40 a night off for 2 nights at a Hampton Inn negotiating for the first time ever. I had a project to write, and the hubs watched the kids. It happened to be a huge little league weekend, so all area hotels were booked and inflated. They had a room for the two nights I needed so I said, "I stay at Hampton Inns all the time and love them, I'm planning to stay in two later this month traveling to and from TN, I live here and am not affiliated with the little league weekend, I have an emergency and we're on a budget, is there anything you can do for me?.." And they did.
Even if yours is just their normal rate, say you stay in there hotels all the time if it's a chain, and you have an emergency, you're calling around for the best price you can get, and ask what is the most reasonable rate they can give you. If they have empty rooms and may not fill up, they will probably bargain. Also check with hotwire.com to get good deals for you, I've used them in the past for huge discounts-but usually in big cities.