We got the refillable mugs at the Contemporary and at Wilderness Lodge. If we like the refillable program, we should not abuse it by cheating (even though soda is such a huge profit item). Use the mug during your stay at the resort it "belongs" to. I used my Wilderness Lodge mug for coffee this morning and remarked to DH that I was glad I chose the "commuter" style (fits in the car cupholder) instead of the slightly larger style because not only did I get all I needed to drink during our stay, but now I have a nice souvenier.
On last visit, the frozen cokes were specifically NOT included in the refill program, but hot beverages and fountain drinks were part of the plan. It's a pretty good deal if you're staying at one resort for several days.But don't just stroll up to any fountain drink station and fill up any old cup -- no one likes a conflict at the "happiest place on earth," and character is who you are when no one else is looking, right?
Have fun and stay hydrated!