UPDATE:
Just got back from Garner SP--it was soo much fun! The AC worked well, but during 12pm-6pm it didn't help at all...but that was no problem since we spent the time at the river.
I once thought that camping in Old Garner was better than new Garner, but I just camped in New Garner and loved it. The sites/restrooms seem to be cleaner and the sites are not as close together as Old Garner. There also seems to always be a nice breeze in the nights/mornings in the new section.
