99% of the time, I either carry my Glock 19 IWB with a Ruger LCR in my pocket as backup, or just the Glock alone. The other 1%, means its cold enough for a jacket (I live in Southern Arizona...so it' probably less than 1%), and I splurge by carrying my full-sized Glock 21 OWB.
I own several handguns, but I don't carry them for 1 big reason. I want to be very familiar with the tool I may have to use in the protection of my life, or the lives of my loved ones. I don't want to be thinking about whether I have a safety or not, or which way the safety goes to take it off, or be surprised by a trigger that's heavier or lighter than I was expecting, or has a mag release in a place I'm not expecting.
YMMV, but for me, my carry guns all have the same manual of arms (in other words, no safety, decocker, etc, just draw and pull trigger) because I don't want to be fumbling around in a critical moment to make sure my gun fires. If you like to rotate your carry guns, that's your choice, and I won't say you're making a bad choice. But I do think it's important to consider the things I've mentioned above and weigh that against the benefits of a carry rotation.
One of the biggest reasons I've seen people use for a rotation is because they can carry different size guns with different types of attire. I call BS on this excuse. 300 days out of the year, I wear a T-Shirt and Cargo Shorts. And I have absolutely no problem carrying and concealing, comfortably, a Glock 19. Certainly, bigger guns are hard to hide, and I wouldn't want to try to conceal anything too much larger than my G19, but it goes to show that you can carry and conceal a duty sized firearm with practically any kind of attire.
EDIT: Check out this thread, and read Pax's response. That is why I don't rotate carry guns.
http://thefiringline.com/forums/showthread.php?t=529568