I agree with euphoricnod, Trainspotting while you're fucked up is awesome.
I haven't tried any Opiates, but when I'm on Meth I LOVE to watch intelligent movies- think Waking Life, etc, you just understand concepts and ideas so much better. I think if you dozed off watching Waking Life you're gonna miss a lot though.
I Heart Huckabees might be good for you, it's a fun movie, certainly makes you think, you probably won't doze off during it but even if you do it's alright.