First, congratulations on winning!
I know you've received a plethora of advice, but here's my opinion...
The Polynesian >> Ah, what can I say? It's beautiful, the rooms are large, it has great views, and it's in a fabulous location. The Poly is also one of the few deluxe resorts with a broad appeal to all ages: its tropical setting is both fun for children and romantic for adults. It has a great dinner show, but you don't have to stay there to enjoy it. As others pointed out, it's close to FW (Hoop-De-Doo), the MK and Epcot (monorail), and various other recreational activities (e.g. boating). One of my favorite reviews of the Poly comes from an old Conde Naste magazine: "It's more tiki than tacky."
The Grand Floridian >> Disney hypes it enough for you to know that it's their flagship resort. In reality, the Grand Floridian exceeds that hype; it's gorgeous. I have personally never slept there (but will soon :sohappy: ), but I have been told that the biggest difference between the GF and the Poly (besides their theming) is that the standard rooms are slightly larger at the Poly. Of course, you probably won't be in a standard room. The Poly definitely wins for location, too; and it's more kid-friendly than the GF. Still, the restaurants, spa, and atmosphere set the GF in its own niche--frankly, I consider it to be Disney's only ultra-deluxe hotel! For me, it's a tie between the Grand Floridian and the Polynesian.
The Contemporary >> It looks nice. It's expensive. But it's outdated, moldy, and loud. Really, really loud. Between the music at the pool and Chef Mickey's in the lobby, the only way to enjoy quiet is to get a garden wing...and then you're not staying in the main tower, which defeats the purpose of sleeping at the Contemporary! As for location, you simply cannot get closer to the MK than this. Although the monorail passes through the lobby, it's faster to walk to the MK, anyway. Regarding the pool and other recreation, the pool is pretty pathetic, especially when compared to those at the GF and the Poly. The recreation is virtually identical to the other resorts, too, with the exception of parasailing; and you don't have to stay at the resort to do that. Frankly, I'd stay somewhere else.
Since I've never set foot inside AK Lodge, I won't review it. However, from all indications and other people's reviews, it looks and sounds like a fabulous resort. Just the same, it's basically located on the far fringe of WDW; and all transportation is by bus. If you're going to stay at a deluxe resort, you might as well stay on the monorail line, even though they do get crowded.
If I were you, I'd stay at either the Polynesian or the Grand Floridian. Their locations simply can't be topped; and you'll spend more time at the MK and Epcot than you will at AK!