I have bought many small insert like posters since they were cheap,but had nice artwork and easy to manage.
North by Northwest
Rebel Without A Cause
The Godfather(international..with a nice collage of stills).
Night of the Living Dead
Army of Darkness
A Clockwork Orange
High Tension teaser insert
I then have full size one sheets of Friday the 13th and The Evil Dead(chainsaw poster) on my wall.
In storage(er packed away in the closet safely) until I have my own place and more wall space are the following full sized posters
Invasion of the Flesh Eaters( aka Cannibal Apocalypse).
My Bloody Valentine UK poster(great artwork)
From Beyond...a Japanese( i think) poster,great twisted artwork
Less Than Zero Austrailian poster with excellent artwork
Less Than Zero Australian insert with American artwork(seller sent me this on accident the first time,so I kept both versions of the poster and was able to score the correct poster at a very low price).