Another thing to keep in mind with the Clairsonic - no matter what kind of brush head you are using, it's important to use the right kind of cleanser. You really want to use a thick gel cleanser. Clarins makes one or two good ones and I personally swear by Rodial's active cleanser, which is pricey, but is very multipurpose for older skin issues. You want a cleanser that stays nice and thick and doesn't immediately break down into a lather, especially a thin lather. The longer it stays in gel form, the more cushioning you'll get from the bristles and vibration.
Another thing, I personally feel it's very important to not use the Clairsonic at night, especially if you have sensitive or irritated skin. Think about it this way: the brush stimulates blood circulation under the surface of the skin. Do you want to bring blood to the surface and then just go lay down on one side or another of your face and go to sleep for hours? At night, you want your skin to rest, not get all "ready for action". If your skin is used to it, you can try adding it to a nighttime cleaning regimen, but I prefer to just use a cream cleanser, like Clarins Extra Comfort Cream Cleanser to gently get off all my makeup and then wake my skin up in the morning with an active cleanser and the Clairsonic.