I've stayed at Pop three times and I don't think I would pay for a preferred room. The first time we were there we were in the 60's section, building 4, 4th floor, lake view. That's my favorite location. It's not a preferred room category, but it's close to a pool, it's a quiet area, great view, and a quick walk to the main building/bus stops. The second time we were in the 50's section, building 2, 4th floor, pool view. At the time, that was not a preferred category room but it is now. While the room was close to the pool (which we rarely used because it rained 80% of the time we were there), it was a bit of a walk to the bus stops and main building but still only about 5-7 minutes. I wouldn't pay extra to stay in that room. The third time we stayed at Pop we were in the 80's section, building 9, 4th floor, courtyard/garden(?) view. This also is not a preferred category room but is a decent location. Again it was a quiet location and wasn't a long walk to the main building. It was a quick walk to the bus stops because we could walk through/along the parking lot. And the pool was very close as well.
I agree with the PP who mentioned that a preferred room does not equal being close to the main building. If you look at the map with all of the preferred locations marked, you can see that there are standard rooms that are closer to the main building than most of the standard pool view locations (that you pay extra for).