Well I do not know if there's already a thread for this (feel free to merge if so).
Nothing like the big screen to really and fully appreciate a film, my experience with SW on the big screen goes like this
A fistfull of dollars
The good the bad and the ugly
Once upon a time in the west
Lo chiamavano Trinità...
...continuavano a chiamarlo Trinità
Trinità & Bambino... e adesso tocca a noi
Renegade (not sure if this counts as a SW)
Preparati la bara!
Il pistolero dell'Ave Maria
I know i've seen others like The Sabata's but not sure, maybe I just rented, but this ones I'm pretty sure. The Leone's I saw it in the Cinemateca National, the others in regular cinemas mostly during beach Holidays when I was a kid.