I love the Pop. I have been 3 times and always had a great experience. I have stayed in the 50's 70's and 80's - so I have seen the resort from all different angles. I was worried at first about having a room in the 80's but location to the busses was actually not bad - we are all adults though and cut through the parking lot to take the shortest distance. We have never paid for a preffered location and don't think we ever would. I think the best location we had was in the 70's - the building with the giant Mickey phone.
Another plus about the Pop is that it is the first stop off the ME - so you come directly there from the airport.
As for thin walls, yes they are, but surprisingly most people don't find them too disruptive. Family members had the room next to mine on my last trip and unfortunately I came down with a stomach bug the last night and needless to say there was a lot of loud toilet flushing that night. I apologized the next day for what I was sure was a massive annoyance, and nobody was disturbed at all.
We are staying at CSR this trip because my parents want to do a bit more relaxing at the resort. One thing I would say about the Pop is that it is a great resort if you are going to be in the parks all day every day, but I don't think it is that convenient for coming back for midday breaks. Plus, the pool at CSR looks like a better choice for my adults only trip than Pop's and CSR is a more central location to all of the parks than Pop is.
Regardless, you will have a blast at Pop - have fun taking pictures with all of the giant props/memorabilia!