Now this looks little weird, but when days pass people starts gifting bitcoin when the popularity increases, one of my friend already has got bitcoin as a gift during the days of Christmas. But with that both were aware of the digital currency and it's value, but the same makes people think what's this gift with the unknown person. So same as we providing giftcard in future people use bitcoin for gifting purpose.
I don't think that Bitcoin is a good idea as a wedding gift not unless that the couple you are giving to is familiar with this one. But if they does not know about Bitcoin, they will surely not appreciate it. I guess you just have to convert your Bitcoins into coins and buy a material gift for the couple. They will surely appreciate that.