Some films shot in the 1950's even had six channel magnetic soundtracks e.g. Ben-Hur and of course were shot on 65mm + film stock so assuming an original copy in good condition survives these should look cool only limited by our 1920x1080 pixel displays.
Older movies I would like to see myself (already got the Searchers BTW) are
Ben-Hur (1959)
Around The World In 80 Days (1956)
Carousel (1956) - Both Camera Versions
Tommy (Quinphonic Sound)
White Christmas (first complete movie shot in VistaVision like The Searchers)
Gunfight At The O.K. Corral (also in VistaVision).
The Ten Commandments (VistaVision again)
For info on VistaVision see
http://www.widescreenmuseum.com/widescreen/wingvv1.htm
HummerUK