I have a tipping question. When you tip valets, how much do you tip, and do you vary your tip based on which casino and what kind of vehicle you are driving?

If you show up at Caesars or Paris, and you are driving a Lambo versus a BMW versus a Toyota Corolla, do you tip different amounts? And do you tip differently if you are at Bellagio or parking at a downtown casino? If you tip different amounts, why do you do that?