Films about stoners are not nearly as good as films for stoners.
My #1:
La Planete Sauvage
Also:
Koyaanisqatsi, Powaqqatsi, Baraka (social art-documentaries)
Paprika, Spirited Away, Ponyo (fun, light, surreal Japanime)
El Topo, The Holy Mountain (Jodorowsky)
Tekkon Kinkreet, Vexille, The Sky Crawlers, Renaissance (more hi-tech, international anime)
Solaris, Stalker, Nostalghia (anything by Tarkovsky)
The Life of Birds (or any BBC nature documentary with David Attenborough)