Thanks! Icons are huge on the App Store, an excellent one is a must have.
We've done some experimenting with marketing, but couldn't figure out any strategy that could convert a bride or groom for $3.50 (the amount we net after Apple's cut). We tried and abandoned Google ads, Facebook ads, and advertising on wedding blogs. Virtually all app-marketing services focus on free apps, and most of them are grey hat in some way.
For a general-purpose app (like our upcoming Party Monster, a more general music app) you don't need to be targeted, but for a wedding app you need to target engaged people, which is expensive!
You may try to contact zankyou or some other website that manage wedding list. I used them for my wedding and they also promote other products. I think they might be interested into your product. Their users are the perfect fit for you : engaged and with an inclination for technology.