I have 6.25 inch wrists, and my advice is go with a leather strap if you are in doubt. The metal bands make anything look bigger.
For years I wouldn't go bigger than a Datejust, but with the current big watch style I have become comfortable with a 40mm Sub and GMT2. On a leather band though I max out with several 42mm watches. 44mm PAMs look comical on me, IMHO.
Also it depends on the dial/bezel design which can affect the apparent size.