Early Candlemass and Skepticism are worth a listen. Skepticism, especially, manages to create profound and solemn atmospheres that reminds me of sylvan landscapes. Very well done, and surprisingly enough, it does not sound negative at all. It's like an ode to the silent forces of nature.
Those two (and a few others like Tergothon) have nothing to do with the depressive kind of doom metal à la Nortt which is indeed boring. They do require a long attention span, however, but that shouldn't be a problem for most people around here.