It's a bit tricky, buildings 14 and 27 are not actually preferred
buildings per se, they are just two out of the four Alligator Bayou buildings which contain mostly Preferred Location category rooms (shown in yellow below). The River View rooms in 14 and 27 (shown in blue below) are only available to guests who have paid for River Views category rooms. The same applies to the Pool View rooms in building 18, and the King Bed rooms (purple) in any of the four closest buildings. (King Bed trumps river view by the way, as you'll see from room 2728 below)
Andre