I do the same thing Deja does, and I have a VERY picky eater!
I have a supply of Science Diet tartar control out all day for her to pick on. I settled on this food after my vet gave it to her as a sample to try (yes, I ended up going to the vet to make sure nothing was wrong, as she just stopped eating all together!)
She's not too thrilled with the Science Diet canned though. Her favorite canned is Whiskas. I figure as long as she has some good quality dry food, that the Whiskas will do as a treat.
Good luck with your kitties. BTW, I've never brushed my kitties teeth either!