I was just on your other thread, and actually, we used our refill mugs at OKW both times we stayed there. Unlike the values, the refill station isn't open until midnight, but it's open quite late. I think I got a refill our last night around 10:30. They usually had the refill station open by 7:00 or 7:30 at Goods to Go. The one at the Turtle Shack isn't self serve and its hours are way more limited. But we definitley got our money's worth out of those mugs, and I wouldn't stay there again and not buy them. Especially if you like to spend time at the pool! But then I have bought mugs for all of our trips, I am a huge ice tea drinker as our my kids so we put them to good use!
I hope you get as close to the main pool as possible. If not, its pretty easy to get around the resort.
OKW is wonderful, your kids will love it.