I am a sucker for polka dots. Perhaps this is due to my childhood love of Minnie Mouse, but there is just something so darn cheerful about them. Here are a few ideas you could incorporate into your wedding without making it seem like Minnie actually planned the event (in other words, don't use all of these ideas):
Wear a veil with just a hint of a dot pattern. This one is particularly sweet and romantic.
Do a monochromatic polka dot pattern on your wedding cake. This cake works well because the pattern is in cream. Once you start using colored polka dots it can quickly turn into more of a kid's birthday cake than the slightly whimsical wedding cake you were hoping for.
Use polka dot straws with your very eco-friendly Ball jar glasses (which handily double as wedding favors).
Have your groomsmen wear a simple polka dot tie with their linen or dark suits. I really love the green and orange ones for an autumn wedding.
Likewise, you could have your bridesmaids rock awesome polka-dotted heels with their A-line black bridesmaid dresses. Perfect for any retro occasion.
If you are having an autumn wedding, use pumpkins as luminaries for dark pathways.