We just booked a reservation for early September, after labor day, and wanted to know where people have had their rooms located in the pop century preferred rooms. We see online that the 60s building seems to be the closest to the skyliner and pool but I've read online it can be any of the buildings 50 through 70.

At Disney’s Pop Century Resort, the 60s buildings (specifically Building 4 and Building 5) are the closest to the Disney Skyliner station. The station itself is located on Generation Gap Bridge, which connects Pop Century to Disney’s Art of Animation Resort. Building 4 is generally considered the "sweet spot" because it sits right between the Skyliner entrance and Classic Hall (the main building containing the lobby and food court). However, some rooms in the 50s section (Building 3) and the 70s section (Building 6) are also remarkably close, often just a five-minute walk away. If you are specifically looking for the shortest possible path to catch a gondola to EPCOT or Hollywood Studios, requesting a room in the 60s section—specifically one that faces the lake (Hourglass Lake)—will put you mere steps from the bridge. Keep in mind that the 60s buildings are classified as "Preferred," meaning they usually come with a higher nightly price tag due to their central location.