After reading Accumulator's posts on this issue, I followed his clay/wax/polish routines during 2006, and was happy with the results. I used the Sonus green clay before adding another layer of Natty's Blue. As winter approached, I noticed a few very minor swirls. Rather than polish with winter coming, I clayed, and used 845 IW x2.
FWIW, I do keep some Clay Magic around for heaverier claying, but have yet to use int on my car.
I figured the swirls can be polished out in the spring (soon, I hope), at which time I will start from scratch. I'll follow the same routine again. I'll clay before adding another coat of wax (haven't decided whether to stick with NB, or try something else). When the need to deal with marring is there, I'll go back to square one.
With better wash/dry techniques, I do not break out the PC as often, and that's probably a good thing.