I used to be a soda addict. Now, I prefer fresh juices and smoothies to anything else! They are so much healthier, frutier, and don't have any of the nasty sugar and acid from soda. I used to go to vending machines all the time, but now, I take it in insulated water bottles(that keep my smoothie COLD and don't even sweat on humid days!). They are the perfect size to carry around, and fit nicely in a backpack or purse(for the ladies)
I love freezing pieces of fruit and then making random combinations for interesting smoothies. Just remember to add a base of regular cold fruit juice(like apple, orange, cranberry, etc)
You can get the bottles at http://www.reusablebagstore.