Pet rats?? :) Advice please!?

I am going to get some new pets tomorrow. I have had mice before, and I have a mouse in my yard right now that I LOVE! I go out and feed it everyday even though it picked my yard because of my pecan trees and loves the leftover nuts. Mice are not common around where I live, or at least people won't admit it. So...mice or rats? Everything I have read says two female mice or two female rats are the best way to go. I'm going with the rats just because they are larger. Anything you can tell me....? They will be totally loved. :)