Hi Jennifer,
I simply love
Disney's Grand Floridian Resort & Spa. I had the opportunity to stay there once, and I fell in love with the Victorian elegance of the resort.
The good news for you is that Disney's Grand Floridian Resort & Spa is not too spread out, so no matter which building you stay in, you should be a fairly quick walk to both Sugarloaf Key and and the Main Building. The buildings that would probably be the closest to both are Sago Cay or Conch Key, with Sago Cay having some rooms closer to the Main Building, and Conch Key having some closer to Sugarloaf Key. Again, the resort is not to dispersed, so rooms in any of the buildings should not be too far of a walk to your parents in Sugarloaf Key.
As to the pool, to my knowledge, the work on the pool at Disney's Grand Floridian Resort & Spa is complete, and I am not aware of any that is scheduled in the future, so go ahead and plan to spend some time relaxing and splashing in the
pools at Disney's Grand Floridian Resort & Spa!
I hope that this information is helpful for you as you plan your trip, Jennifer. Please do not hesitate to ask if you have any further questions.