Stayed in La Quinta at my folks new house and hit a few different places. Just off of Highway 111 as you enter Indio, is Shield's Date Farm, reviewed on Roadfood. Date shakes there are great, not overly sweet.
Further East on 111, On Towne Avenue, is a place called Teresa's Cafe. Great basic Mexican food, with a killer Chile Colorado and quite good tamales. Priced very reasonably, this is one of the better Mexican restaurants that we have tried. Just a cash register and uncovered tables and chairs (no bar, no alcohol), in a tough neighborhood, it's about as "roadfood" as you can get.
Another place that I really like is The Fisherman, which has 4 different locations and is some of the best seafood that I have ever had. It is a very casual place, but the seafood is phenomenal. On various days, we had melt-in-your mouth fried calamari (the best I've had) a cold gazpacho like soup called Campechagna, loaded with avocado, scallops, octopus, squid, and shrimp (excellent), raw cherrystone clams, and clam chowder (pretty so-so). The menu is huge, ranging from fresh fish entrees to lobster and langostino tacos. Great place.
Stopped at Tyler's in downtown Palm Springs (Indian Canyon Road) for great burgers and fries. Opens at 11:00 a.m., and by 11:45, the place is packed. Try the homemade cole slaw there- it's top notch.
Went to San Diego for a day and stopped at George's at The Cove for lunch in La Jolla. Had an outstanding soup, with black beans, broccoli, and chicken. Good place, not roadfood, and not cheap.
We stopped at In-and-Out with the kids twice. The kids like their burgers with ketchup only, and I tried them. The burgers were crusty and not juicy on both occasions (at two different places). I don't remember them tasting this bad. The fries still suck there, like usual. How can fresh-cut fries be so soft and tasteless?
While the Palm Springs area is fraught with high-end steakhouses and restaurants, there is quite a bit of good Roadfood in the area. We missed the Wheel Inn and a place called Hamburger Mary's and Cactus Jack's (both known for their burgers) this time, but I will hopefully catch those next time I'm on a golf trip out there.