Hi,
I go there at least 2-3 times a year, and have for the past 25 years. The vis is very good on the outside reefs, normally between 70-100+, but this depends upon time of day, tides, and mainly what the weather patterns are in the region.
The vis at German Channel, Ulong Channel, and some other sites are very dependent upon tides and the vis can range from 30-70'.
The winds
usually shift to the southwest from Oct-December, making the most popular sites (Blue Holes, Blue Corner, Big Drop, etc.) a little challenging due to swells. The key word here is "usually".
As others have said, you won't get anywhere near 80' on the wrecks. Expect 25-50'. But, IMHO, if you're gonna dive wrekcs, go to Truk (Chuuk). Much better wreck diving there by a mile.
To see a bunch of Palau videos, go here:
Palau Travel Videos
Hope this helps.
Pete