I don't really rotate carry guns. But I do have several for different purposes.

Lightly modified Pre-70 Series Colt Commander .45acp. My primary carry gun.
S&W 642 .38 Special: For hot weather and when I just feel lazy.
Colt Mustang XSP .380: I carry this on my daily exercise walks. With its poly frame and stainless slide, its about as sweat proof as a gun can get.

But, sometimes I get a wild hair and might carry anything from a .25acp to a .45 Colt. Just depends on my needs and my mood at the time.