Column bases are something I've already been thinking about a lot. Free standing decks need as much bracing as you can give them. There are a variety of Post/Column bases over at Simpson Strongtie. I've already selected mine.
The CBSQ66-SDS2HDG. The bottom half is embedded in the concrete, and the top straps go around the 6x6 posts I will be using. Lot's of strength there. Simpson does make a point of stating on all their bases that they are not designed for decks without top support. So these are no substitute for bracing, but they should provide excellent strength.
Notice the HDG in the name. Mine are HDG - or Hot Dipped Galvanized. We live within 3 miles of the ocean. That means metal will corrode VERY quickly. Even "Stainless" outdoor things rust here. HDG are coated in Zinc, which should hold off the rust a lot longer. Ideally everything would be 316 marine stainless, but that's not practical for heavy pieces of metal like this.