My room was too sweet and traditional to have anything attatched to walls or ceiling.
My Fortress of Solitude (a.k.a. the playhouse,Cindy's barn,etc.) had posters on the ceiling and every vertical square inch that wasn't used for books or storage.
We didn't have access to many 'storebought' posters (especially the more outre ones) but I had Peanuts,Argus motivational posters,centerfolds from 16 and Tiger Beat,Civil War and art prints (Klee,O'Keefe,Munch,LOTS of Maxfield Parrish,Rackham,Deco/Nouveau stuff) and animal posters.
I also had movie posters from Famous Monsters of Filmland (Metropolis,Forbidden Planet,the Universal pantheon,Dark Shadows,etc.) and a substantial amount of 'homegrown' art.
My friends and I copied the stuff we couldn't get otherwise.
We would do reproductions or homages to every comic panel,
album cover or whatever we liked-from Steve Ditko to Peter
Max to George Rozen -and did our own versions of psychedelic
and pulp motifs.
The decor very much reflected our take on the era we were
just-too-young to participate in.
Eclectic,colorful,derivitive,idealistic and rather innocent.
Elvis next to E.T.
Patriotic posters next to photos from the Southern Christian Leadership Conference.
Harlem Renaissance and WW2 posters next to Keene-eyed urchins and poker playing dogs.
We were a little more insightful and infinitely more kitchy
than we knew.