I agree with black562...you can find a bar pretty much anywhere in Disney. However, my husband and I continue to find ourselves returning to a place I would never think I would like. There is a Margarita Bar at Downtown Disney Marketplace. They sell margaritas and the most wonderful rum rummer I have ever had (which is pretty good since I hate rum). They have tables with umbrellas right next to it that are right by the water. It is gorgeous at sunset. It is not fancy and not technically a bar but I find myself going back year after year.
BTW-that rum rummer is $8...pretty average for Disney. I find in Disney your gonna pay the same amount for a pina colada at the pool bar as you will at a lounge.