I always thought standard, plus, premier was simply floors 1, 2, 3, respectively. But last summer I did a deep dive into the resort info someone had shared on Kohala here a long time ago, and this is not exactly the full explanation.
The standard units are always in buildings #3 and #4 (the two buildings that back to Waikoloa Beach Drive) and they can be on any floor. There are no plus or premier units in these buildings.
The plus units are always in buildings #1, #2, #5, and #6 (the four buildings that back to the golf course) and they are all of the ground floor units and the interior (non end) units of the second floor.
The premier units are always in buildings #1, #2, #5, and #6 (the four buildings that back to the golf course) and they are all of the third floor and the end units of the second floor.
That being said, my favorite stay I've ever had at Kohala was in a "plus" ground floor end unit in building #6 at the very end of the entire property (this is either unit #1911 or #1918). The lanai is larger and not walled off on one side (pictures below)...