Sorry I am late to this party…and yes, the Imperial Palace has gotten a bad rap. I know a woman who works there and she has told me they have started renovating all of the rooms, so looks like they plan to stick around for awhile at least. Plus, don’t miss the cool car show there…even if you aren’t a big car fan, it is fun to walk through (and you can get free tickets if you ask or look in the local magazine on your nightstand).
Most everybody has given you good suggestions…and considering it is just a quick one-night stay, I too would just go on-line and pick someplace clean and cheap. There are some new Marriott Hotels south of Mandalay Bay on the other side of the freeway - with no casino or whatever, but they might be a deal as well. Plus you might look into the Silverton or South Point (both south of Mandalay Bay on the I15, the route to Palm Springs).
Have fun in Palm Springs and in Las Vegas!