^I'll definitely check out "The Addiction," thanks. I somehow never heard of that but it sounds like something I'd be really into.
I've been putting off responding to this thread because I've been trying to think of what films have atmospheres similar to David Firth or Scorcese (plus I knew it was going to take a while to craft this monster post). But I guess since those are so different from each other you're probably open to lots of others, AppleCore?
Out of all the elements of film, I've probably been motivated most in my search by a lust for thick novel atmospheres. There's something profoundly fascinating about them. Unfortunately, the horror genre -- often impoverished in other areas -- is where I've found most of the efforts in the art of atmosphere concentrated (which is only natural, as the nightmare provides so much of the inspiration within it). "Susperia" is among the best examples from horror. I liked the two sequels, too: Inferno, and Mother of Tears (I'm in a minority with regard to Mother of Tears, though).
Here's two great shorts by Jan Svankmejer for anyone just looking for a sample:
Down to the Cellar
Lightness, Dark, Lightness
I agree with most of the recommendations so far, esp. "Inland Empire".
Anyways, here's my recommendations when atmosphere is the priority above all else (I've tried to include some that are lesser known or may not typically be considered):
"Destino": This short film was a collaboration between Salvador Dali and Walt Disney. It played before the theatrical version of "Triplets of Belleville".
Wizards (and other Ralph Bakshi, esp. Heavy Traffic)
Takashi Miike's "Box" (one of three short films in "Three Extremes")
Also by Miike, "Izo". It's about a betrayed soul's journey to end existence by destroying karma, which in the process becomes a new principal of reality-- I think. It's one of the most extreme and bizarre movies I've ever seen. A bit discombobulated, yes, but with moments of manic intensity and super-saturated mood.
David Cronenberg's "Existenz"
Rob Zombie's "House of 1,000 Corpses" and "The Devil's Rejects." Zombie gets lots of hate, but if you love the haunted house carnivalesque nightmare aesthetic he's great.
"Taxadermia," but not right after you eat. "Hukkle" is another great but very different surrealist work by the same director, György Pálfi. Keep an eye on him if you like surrealism.
"Malpertuis" This one's almost unknown, but highly surreal and well produced. It takes place in a mansion with all sorts of hidden hallways and haunted portals with monsters from Greek myths. With Orsen Wells!
"Delicatessen"
"Uzimaki Spiral" (the horror is the metaphysical shape of a spiral! Very unique.)
"Blood Simple"
"Visions of Frank" "
Whim Grinder"
Tarkovsky's "Stalker" (very philosophical)
