We have stayed in both, and loved it!!!
Last summer, we stayed in the 60s since my DH & DD love the 1960s! Our room was on the 3rd floor, overlooking the kiddy pool. Our room was very quiet and clean! It was a short walk to the main bldg & bus area.
In Dec and again in June, we stayed in the 50s bldg - with Lady & The Tramp. It was very quiet - in Dec, we could see the fireworks from our room. In June, we were on the 1st floor, near the parking area. Both rooms were very quiet - we never heard our neighbors!
We really enjoyed all of our stays. I don't think I would necessarily pay the extra $10 for a preferred room. The 50s bldg was a short walk to the main bldg & bus stop area.
Again, we had some great times at the hotel! We're hopefully headed back in October (depends how fast we can recover from Hurricane Katrina).
Enjoy your trip!!!!