I haven't stayed at either, but the general impression I get on these boards is that SSR is undesirable. And I'll tell you that whenever WDW offers free upgrades because of construction or overbooking it seems like the first thing they offer is SSR, so maybe they have trouble filling those rooms.
Here's what they say on mousesavers:
Old Key West is my Best Value choice in the Disney Vacation Club category. It was the first Disney Vacation Club to be built and the units are a bit bigger than at the other DVC resorts. Yet Old Key West offers the least expensive rates of the villa resorts on Disney property. The themed pool at Old Key West is spectacular, there are nice dining options and overall it's an extremely attractive resort with lots of stuff to do.
However, I only recommend staying at Old Key West if you will have a car. Otherwise it feels a bit isolated and it's not at all convenient to eat at another resort, go to Downtown Disney, or attend special meals such as the Polynesian Luau or Hoop-Dee-Doo Revue. Also, you may have to walk long distances from some of the units to the restaurant and main pool -- if you have a car, you can drive over and park near these central services.
My least favorite of the Disney Vacation Club properties is Saratoga Springs Resort. The location is somewhat remote and it has the smallest units of any DVC resort. The large number of units (and their location) means long walks to the central area that houses the pool, food court and spa. Also, the theming at this resort is fairly ordinary, in my opinion.
The only major advantage of this resort is that you can walk to Downtown Disney. I recommend renting a car if you stay here. Otherwise it's not at all convenient to eat at another resort or attend special meals such as the Polynesian Luau or Hoop-Dee-Doo Revue.