I'm just starting to offer Wedding cakes and wanted to know if sponge cakes should be marzipanned as fruit cakes generally are?
The marzipan smooths out the rough surface of the fruit cake, as well as a few other things. That's not really necessary with a sponge cake.
Also, the marzipan adds a good bit of weight and many sponges wouldn't hold up well to that along with the weight of fondant/sugarpaste.
If you don't want to use buttercream, some people just put sieved apricot jam on the cake under the fondant.