Great decision! We have stayed at the Poly several times. and am not sure if we would stay anywhere else! It would be nice to try another resort, but the kids just love it at the Poly.
I love the look of the WL (been there only for dinner), but would miss the monorail and the fireworks from the beach! You can also walk to the Grand Floridian and the TTC from the Poly.
I think you made a decision you will be happy with!!
The grounds are so beautiful!