Our boat has been on two circumnavigations (so far!) with 60 meters of G40, and an additional 100 meters of line.
Cruising this boat in the Caribbean and US East coast we haven't yet used all the chain. Anchorages in the Pacific tend to be deeper, and more is better.
That's what we have... If I was equipping the boat myself from scratch I'd go with 80, maybe even as much as 100 meters of chain and groan a lot about the excess weight... until I really needed it!
Fort Lauderdale, FL