First ever River Cruise is booked! AMA cabin waitlist question

After much thought on taking a cruise for a major birthday (how did I get to be this old!?).... we came down to Windstar (have done 2 cruises and love this line), Seabourn (Med tour with Spain in the itinerary) or SeaDream (same thing). We also considered a rivercruise, but it seemed that all the river cruises in our timeframe (late Sept/Oct2013) were booked. Windstar did not have an itinerary that we liked in our timeframe, the timing/itineraries for the other 2 ships weren't ideal for us.

I called AMA directly to find out if they had any availability in our timeframe and ideal itinerary - Budapest to Prague. Someone must have just cancelled because there was one cabin on one ship in a 5 week timeframe! It is not our ideal cabin, AMAcerto D category, but we are excited! We would much prefer a C or BB. Anyone have experience with the waitlist ***** AMA for cabin upgrades?