I've played both several times, I'm with Joel. I don't like Nicklaus courses and while Mayacama is one of his better ones, I still don't think it's Top 100. Some of the holes there are mediocre, and a couple (including a Par 5 on the back) just made no sense to me at all. 8 of us went out there last fall and played it, not one of us liked the course. Still, the setting is very nice, the facility is one of the nicest I've ever seen, and it's a good golf course.
Cordevalle is a good course too...I actually like walking it, and they have caddies there as well, it's not a carts only place by any means. A very nice facility with great food, not quite the level of opulence that you get at Mayacama, but still quite nice. The setting isn't as lush as Mayacama. I prefer Robert Trent Jones courses to Nicklaus courses, so if I had a choice of courses, I'd pick Cordevalle. Overall experience including the dining area and setting, Mayacama gets the slight edge.