I have usually called a few days before our arrival (Member services) and had requests noted.
Our last stay in July we arrived early and our room was ready in The Paddock. We really wanted Grandstand, as we had an awesome overlook the Grandstand pool view in April, so I asked at the desk if there was anything available in Grandstand instead (in a nice, non-chalnt, and polite manner of course). The CM told us that nothing was available unless we wanted to wait until later in the afternoon, we decided to wait for our wanted section and once again lucked out being next to the Grandstand pool.
Sometimes it works out to call ahead (I usualy note my area in order of preference for SSR: Grandstand, Springs, CP) and that is my only special request for SSR, and other times you get what you get (as noted before us choosing to wait for what we wanted even though I had called ahead).
However, if my request was never met, I'd still take it in strdie....I'm just happy to be at Disney.