Michael-
That is a good question.
As sites were converted from full or preferred to premium, a lot of trees were removed, but the basic site footprints were not changed. So, the loops that were more crowded before are still more crowded now.
In my opinion, the sites in 400, 500, 900 and 1400 are the tightest. Also the old part of the 600 loop has some tight sites.
That would leave the new part of 600, 700, 800, 1000, 1100, 1200, and 1300 as the premium sites with more generous space between the sites.
TCD