So I've read many threads over the years about people inquiring if this is possible. I checked into Riverside today and was able to switch from a standard Princess room to a preferred room in Alligator Bayou. Watched Disneys booking sight like a hawk for months to see if preferred rooms opened up with no luck. Asked awesome cast member Trudy at check in, she called equally awesome Chrissy and were able to do it within minutes. Not only did I save money but I ended up with building 14. Riverside fans understand significance of 14. So it is possible, especially when done politely.