Hands down if you are going to get a smoothies head to Rawesome Juicery (Sweet Auburn Market), there you are limited to smoothies only because the juices are already bottled up. They are always patient and understanding. I even bring my own containers and the staff will place my wraps and zucchini pasta into my Tiffin box.
Newbie on the block is Doctah Mojo's Juice Clinic (Irwin Street Market). Lastly, my girl Shana BKA Your Vitamin Lady (Sweet Auburn) sells fresh juices and elixirs like blueberry lemonade and basil raspberry juice, and their always willing to serve it up in a cup that you bring.