I don't remember if S/D have a hot tub, they have a number of different pools, but we've only used the Grotto pool.
As far as other benefits, after location my fav. benefit is the amazing views. We had a corner room last time and watched Illuminations fireworks from bed. Both times we were upgraded, for free, to the most amazing views of BW, MGM and Epcot.
The poolside restuarant is one of our fav. places to eat. Nice gamerooms in both resorts. Lovely beach with volleyball and hammocks. I believe there is also a kiddie area with squirting sidewalks.
People have complained about too many conventions, but we have yet to notice any. As a matter-of-fact, we've run into more conventions/weddings at Contemporary and GF.
Let me know if you have any further questions and make sure you check out Glo's fantastic S/D site. I'm a huge Dolphin fan, mostly b/c I expected to absolutely hate the place and still can't get over how amazing it is. Make sure you check out the shooting stars in the lobby, I can't wait to see them in June.