I have two :
1. The Sound of Music - The stupendous marriage scene with marvellous music and the nuns singing "How do you solve a problem like Maria
2. Love Story - where Rodney and Jenny exchange vows quoting poetry ; I find this a really moving scene.
GREAT ones! I know you meant Oliver...
while you were sleeping
Right off the top of my head, it's not the elaborate here-comes-the-bride type... The wedding scene in "Braveheart" where William & Murron are married in secret by the priest in the forest, just the three of them is sublime.
Bella's "real" wedding in Twilight was a beautiful affair.