Pennykay,
The second floor has a great advantage in that is on the same floor as the lounge. You don't have to walk up or down stairs (or use the elevator) to access it. 2 years ago we stayed on the 2nd floor, lagoon view. I had requested first floor but the only first floor room available had a terrible view of the castle so I asked to be moved. At first I was bummed out that we would be on the 2nd floor. However, we had a fantastic castle view and the convenience of being on the same floor as the lounge more than made up for the lack of a balcony. I still can't figure out, however, what the designers of the Polynesian were thinking when they decided to exclude balconies on the 2nd floor of each longhouse! We were in room 2507 and loved it. The advantage to the 3rd floor would be, in my opinion, better overall views due to the higher elevation and of course the balconies.