While butter cream frosting has been one of the most widely used wedding cake frostings, you cab opt for almost any variety of frostings and fillings.
Cream cheese, buttercream, marzipan, and flavored frostings are big hits.
Frostings that need to be refrigerated, like cream cheese, should not be used in spring/summer outdoor wedding receptions.
Your cake baker can recommend fillings that go with your cake choice and frostings that will work for the design you choose.
Frostings for chocolate cakes offer the same versatility for designs as other frostings.