I like detailing the wheels/tires/wells. For me it's just really satisfying to dress the tires and fenderwells and seal the wheels after they have been cleaned perfectly.
It would be both; it's the finished product in my eyes and the finished product in the customers eyes.
I like getting the check!:woot: Really, I like the end result, when the customer comes out to look at the vehicle and is floored by the transformation. Always makes me feel good.