Movies I've seen the most:
The Court Jester
Chinatown
Rosemary's Baby
North by Northwest
others.
But - movies I saw over and over again when they first came out - which means I either stayed at the theater (in the days when you could do that), or I just kept coming back to the same theater, or I'd follow the film to various other theaters from first run to the nabes - it might be a surprising list - it is to me:
The High and the Mighty
The Court Jester
North by Northwest
Li'l Abner
Fahrenheit 451 (three times in one day)
What's New, Pussycat
Modesty Blaise (the oddest movie - it really doesn't hold up but back then I found it very stylish and very amusing and I went to ever theater that played it)
That Man from Rio
The Umbrellas of Cherbourg
Sundays and Cybele
The Miracle Worker
David and Lisa
There are, of course, more, but the winner would have to be: West Side Story.