Intelligently written?
OK so let's start with the Japanese stuff. Assuming you've seen The Ring remake, forget seeing
Ringu (the original). Now if you
haven't seen the American remake, absolutely rent the original.
The same director also did
Dark Water. Again, avoid the remake at all costs -- the original Japanese version is truly excellent.
(You should enjoy both those even if you didn't like Audition).
Also, you MUST check out Guillermo del Toro's
The Devil's Backbone. I've been plugging this guy's work for years now. As you might have seen, he also recently directed Pan's Labyrinth and it's supposed to be oscar-worthy.
Shame you didn't like The Changeling. However, keeping in line with all things George C Scott (because there's no denying he's one of the greatest American actors of all time), you really should see
The Exorcist 3. Totally underrated, and superbly written. It also takes on the 'serial killer' vibe so since you liked Se7en, you should love this fucker.
Here's a long shot to round up my five for you......consider
Event Horizon. I've only seen it once but remember liking it very much. I've since heard people say it's one of their favoUrite. Amazingly, it's written by Paul S Anderson, the same cunt who ruined Aliens vs Predator and the Res Evil series, but somehow he got it right for this one. Again, it's got that same 'crusty' feel to it as Se7en, in fact, when watching it, I was reminded of the same creepiness I felt whilst playing the first Silent Hill all those years ago.
So there you have it:
Ringu
Dark Water
Devil's Backbone
Exorcist 3
Event Horizon
