i've stayed at pop a few times to know what i like and what i dont...
i've stayed in 50's buildings 1 and 2. loved them both. very short walk to the main hall with a few added steps to transportation. would strongly recommend this location.
i've also stayed in building 8, the only 90's building. the only complaint i'd have is the distance. its not terrible, but not convenient. the shortest walk to the transportation area and the main building is through the parking lot -- cutting between parked cars. not fun.
overall great resort, i'd take an overnight stay in building 8 again over a day at my desk working -- enjoy!