I'll tell you we did very much miss a hot tub during our summer trip to the Poly (it was memorial weekend and hot as all get out). For one thing, the Poly pool was freezing and my kids who are skinny and always cold, love being able to switch over to a hot tub when they get too cold in a pool.
All that said, the Poly was so amazing we did enjoy it. But other than the awesome view of the castle from the pool area, the pool area itself was a big disappointment. I think it is that resort's weakest link and I must say when we switched over to Old Key West later in the trip, we were very glad to have that pool and its hot tubs. Even without the cool view! But the rest of the resort made up for its pool area and we loved the experience and would definitely stay there again. But not in the winter when a hot tub is even more key for us.
If Stormalong Bay is no biggie, but that Epcot area is, have you considered Boardwalk? Since its a DVC resort it has a hot tub in its quiet pool too which is a lovely, peaceful quiet pool. Of course BC's quiet pool has a hot tub too I believe.
Oh yeah, we have been to WDW in hot and humid months and all of us enjoy the hot tub at night. Good for my skinny kids, good for mom and dad's tired feet and backs!