Our last 3 trips (all earlier this year), when we checked in we asked about upgrading to club level. Each time, the front desk CM called someone to check availability. Our rooms were all booked with a substantial (around 35%) AP discount.
At boardwalk in feb, there was an upgrade available, but only to one of those large 2-story suites (i forget what they're called - garden cottages?). The upgrade was several hundred dollars per night, so we declined.
At gran destino in july, the only club room available was a 2 bedroom suite, which we again declined because the price was very high. However, the front desk CM told us that if they had had regular club rooms available, the upgrades had been going for about $100/night.
In aug, we stayed at contemporary for one night when attending the star wars preview. We asked about club level and were offered an atrium club room for $75, which we did agree to. It did not seem to matter we had payed a low (for contemporary) AP rate; our original rate plus the $75 extra was still way less than rack rate for our original room. I suspect they had a last minute cancellation, as someone else's personalized itinerary showed up in our room with our room number on it. Still, i was happy to take advantage of it.