There is only one resort in KW on the DVC RCI list. It is the Galleon. I haven't seen it but from what I gather it's a good but not great resort. The Hyatt's are the better options but are in II. RCI and DVC only has 2 resorts in the Keys total, the other is the Bluegreen resort on Marathon, likely a better choice in resorts but you may not like the location as well since it's not in the action area. I'd look for a rental or a direct exchange with a Hyatt owner.
Thanks so much for the info! We're celebrating our 10th wedding anniversary in 2010, have some points to use up, and had a great trip to Key West while we were dating... We'll look into these options. Thanks again!
If the Marathon resort interests you, you might consider a direct exchange with a BG member also. I looked online and I'm really not seeing anything for the keys except one resort I likely wouldn't stay at in Key Largo. Key West is a very difficult place to trade to even for off season due to he limited number of resorts and overall high demand.