For a girls only trip - Grand Floridian! It's the ultimate Disney girl resort IMHO. Beautiful Victorian style, tons of wonderful restaurants (try the afternoon tea!), great pools and right next door to MK. We treated my sister to a stay at GF last year and it was definitely a "ladies" trip! Princess meals, afternoon tea, etc.
WL's rooms are quite small and don't have the transportation advantage of GF. I really like Poly, the theming is wonderful, but GF does offer much more in terms of amenities (more restaurants, every room gets turn-down service, etc.)