easiest thing to do is to head north out of town and go over the interstate and hit Dillon Road. From downtown P.S. to Dillon, then all the way to the end of Dillon and back is about 70 miles. It is a bit rolling, but not overly difficult unless the wind kicks up. Mike Plumb, TriPower MultiSports Professional Running, Cycling and Multisport Coaching, F.I.S.T. Certified http://www.tripower.org
I was in Palm Springs about a month ago and hooked up with the Desert Bicycle Club. I did the Thursday and Saturday rides and had a blast. Some of the guys there like to hammer but I believe the groups split up and it's easier at the back. On Saturday they actually have three rides and I imagine the slowest one is pretty chill. The guys I met were super nice and I'm glad I met up with the group as I wouldn't have done the same routes on my own. Anyway it's worth sending them an email as even if you don't ride with one of their group rides I'm sure you can get some suggestions of where to go.
The club website is http://www.cycleclub.com/ and the president is Gary. He's the one who responded to me when I sent an email to the address on their homepage: cycleclub@yahoo.com