We went last summer. Our request, noted on our reservation by our
travel agent when we made the reservations, was 3rd floor Fiji or 3rd floor Rarotonga. I did complete online check in and noted 3rd floor and balcony as my two preferences. Finally, I used the Touring Plans fax and used the phrasing that they recommended to request 3rd floor Fiji marina facing, starting with the specific room we wanted and then fanning outward from that room. We were assigned one room over from our first request and were extremely pleased with the results of everything. Who knows which part of the request was honored, but being one room over from our request through TP seems too much of a coincidence. Of course, we were there in August and it wasn't sold out, as far as I know, and YMMV. But I wanted you to know it can work.
I chose my room request mostly because of Tikiman's awesome advice at that time as to how to avoid construction, so I need to thank him here! It was an awesome first vacation for our family at Disney and we are headed back this summer again!