Napoleon's Triumph is a brilliant, but mind-bending design. Take a look at Guns of Gettysburg by the same guy. Also brilliant, and feels more intuitive. Longer, though, if you play out all three days. At least the board is smaller. :)

Twilight Struggle has a great period feel, although some of the mechanics are a bit clunky (realignments seem mostly unused, and yet the map is made for them). Haven't tried the COIN series (Labyrinth et al); the design seems really solid, although people should probably note the slant in the "politics" of the game. But that shouldn't bother too much even if you disagree on the emphasis, since gaming is all about what-if's anyways.