If it's really going to be a big deal for you and impact your trip, I would pay the $ and get a preferred room. When we stayed at POR, we were not granted any of our requests (none of them would be considered an upgrade, just a matter of convenience). It ended up being a real issue for us, and I definitely would have doubts about staying there again for that reason. The resort is just SO spread out, we felt like we weren't close to anything (pool, bus, main building, parking lot).
On the other hand, we just got back from CSR, and not only were we granted our requests (1st floor, Cabanas), but we were upgraded to a waterview - it was a great room. But we were there celebrating DDs birthday, so I don't know if that had anything to do with it.
I would recommend online check in since it will allow you to (again) note your requests, and if you get there and don't like the location, it can't hurt to ask to change!
Have a great trip!