We like the pools at the Swan/Dolphin, the quiet pool at BWI, the quiet pools at POR, and even, much to our surprise, the pool at the CR where we enjoyed the view over Bay Lake (even though the pool itself is plain it was never crowded nor chaotic like some of the more themed pools). Both pools at the GF can be lovely as well. I agree with Nancy56 that the AKL pool is really nice.
Overall, for adults only, we usually stay for at least part of our trip in an Epcot area resort. Access to World showcase in the evening is a big plus and the pools are as nice in this area as anywhere on property. Storm Along Bay is wonderful, but can be crowded and is spread out. Our choice is usually BWI or Swan/Dolphin.