Take Game of Thrones. On inspection, it's an odd sort of series to theme a wedding on - and yet there have been a fair few weddings in the four series shown so far.
x marrying x . x marrying Joffrey (and we know what happened at THAT reception. x marrying x (another reception that didn't end quite as planned. Tyrian Lannister marrying Sansa Stark.
However, the 'cloaking' ceremony in Game of Thrones where the bridegroom covers the bride with his cloak is rather romantic - so we can see why some couples want to include this on their wedding day.
Personally if I was going for a TV or movie themed wedding day and I was a fantasy fan, I'd probably go for the wedding in The Lord of The Rings when Aragorn marries Arwen. Fabulous costumes, a happy ending and plenty of ideas there.
If you're a fan of dancing and the pair of you don't mind showing off, then you could replicate Burt and Carole's Glee wedding when they danced down the aisle after the ceremony. That would certainly be different!
The Little Mermaid - if you're a Disney fan. Or you could do Robin HOod and Maid marion (see film clip).Cinderella and Prince Charming.
Sex in the City - really for the bridesmaids - mismatched dresses and looks fabulous.