So, Ryan Reynolds' best movie of 2011 definitely isn't Green Lantern or The Change-Up. It's the documentary The Whale, which he executive produced and narrated. It's about a baby orca that got separated from his family and ended up off the west coast of Canada. It's a bit cutesy, but that whale sure is lovable. I reviewed the film for Screen International.
(Update, March 2023: If you're looking for the other movie called The Whale, go here.)