I book with priceline for those one-nighters. The last time I did that I got a hotel near Universal for $27 which was pretty decent. We had a suite so extra space in the room, a free hot breakfast of everything imaginable, and there was a nice tikki bar with homemade burgers etc.. set up at the pool in the evening. It also had a free shuttle to Universal, but we didn't need that.
I think the regular price was around $85 per night.
ETA: For those who prefer to use hotels.com -- hotels.com has a coupon code for 10% off : MAYFLOWERS10
Book by May 11, 2011, travel by Nov 17, 2011.