Aside from those already mentioned, a couple that stick in my mind are Zoo de la Barben, because it's tough to beat a hilltop in Provence (chateau included), and the Smithsonian Marine Exhibition Center, with 360° views of the Atlantic Ocean, downtown Panama City, Frank Gehry's Biomuseo, the Bridge of the Americas, and the western entrance of the Panama Canal.
To echo reduakari, though, Monterey Bay really does take the cake. That location is just perfect.