Just watched George Romero's 1985 Day of the Dead. It is the least discussed of his Zombie masterpieces. Night of the Living Dead is of course both the genesis of the modern Zombie movie as well as the benchmark. The original 1978 Dawn of the Dead is also considered a classic. However, as I see it,"Day of the Dead" although planned (from what I have heard) as the third of a trilogy has gotten short shrift. Last seasons Land of the Dead was wonderfully executed and an extension of the myth of Zombiedom.(particularly with it's theme of Zombie development) But "Day" for this cinema consumer is Romero's darkest vision. With it's subterranean setting and edge of sanity performances, it is a must add for your queue.
PS: Sherman Howard's performance as Bub is a stand out.