There is a modest diseconomy of scale in marginal cost going from the 20 oz. size to the 24 oz. size, the reason for which eludes me. That in turn bothers me at one level (I teach in a business school, so I feel that I should understand pricing models) and not at another (I occasionally fly on commercial airlines, whose ticket pricing algorithms appear to be the first "practical" application of chaos theory).
Obviously, being an O.R. person (and a business prof at that), I was compelled to order either the 20 oz. size (best marginal cost) or the 24 oz. size (best average cost). Thus do I, being perfectly rational, give the locker room scale one more reason to shudder when I walk in the door. I did order a reduced-calorie version, which is somewhat like playing stickball on a busy one-way street as opposed to a busy two-way street.
Update: I'm now sitting in another coffee shop, where I buy beans. They have a pretty sweet deal: buy a pound of beans (slightly more expensive bargain brands at the local supermarket, but not much more) and get a free drink, any type, any size. I'm not sure exactly how many ounces in this drink, but the fact that it has its own lifeguard on duty is not a good sign. I truly do not want to think about how many calories it contains.