Tired of the limited selection? It's bad enough that they are limited to one company, such as Coke. I see many Coke machines around here, some are cans, some 20 oz bottles. Out of many buttons (12?) you get Coke and Diet Coke, and if you're lucky, vanilla coke.
No other flavors, and none of the other Coke owned drinks.

The decision on what to put in the machine is up the company that fills the machine -- which may or may not be the bottler.

Usually Coke will have 2-3 machines in one location, which allows for more variety. I usually see Cherry Coke, Barq's, Nestea and Dasani in machines in addition to Coke/Sprite/Diet Coke. If there's a machine with non-carbs in it, there might be 2-3 flavors of Minute Maid along with the Nestea flavors.

Call the number on the machine and complain if you don't like the selection, that's the best way to get something added.

It would be nice if some independant distributors could set up glass bottle vending machines with a nice assortment of flavors. You could select between sodas like Moxie, Cheerwine, Cool Mountain, Root 66, Afri-Cola, Bubble Up, or Red Rock Cola.

Tri-City Beverage in Johnson City, TN has vending machines that spit out *only* glass bottles. The one's I've seen were stocked with Dr. Enuf/Gordon's/Charlie O's in 12oz bottles.