Day of the Tentacle was one of favorite adventure games ever, but there was really something special about Grim Fandango. Off the top of my head, I can't think of any other game that combined superb art direction, music, ambiance, story and memorable characters to the same extent as Grim Fandango.

I don't think it's too much hyperbole to say that Grim Fandango was the swan song of an entire genre.

Now I'm getting sad :(