I'm trying to find a good recipe for a wedding cake. I'm going to keep it fairly simple, one or two tiers, plain icing with some small decorations.   Many recipes seem to be variations on classic fruit cake or Christmas cake. Is that the case? Am I safe scaling up a recipe like Delia's Christmas Cake (a favourite of mine) or is there something specific about the flavour of a wedding cake I need to be sure to include or omit? 
Traditions for wedding cakes have varied so much over time and throughout the Pretanic Isles as to make "the tradition" impossible to settle on.  Having different cakes for different tiers is both long-standing and popular today, as well as being of practical benefit (having a relatively solid cake like chocolate-biscuit at the bottom for example).  Fruit cakes go back to the when Bride's Pie stopped being savoury, and have secondary traditions associated with them (its sometimes done to store the smallest cake layer in brandy and use it as a Christening cake for the first child born to the couple) which may make it a particularly desired choice. It's common to have it in the mix for that reason. A cake like Delia Smith's Christmas cake would certainly be in line with that.  Of course, one of the oldest wedding traditions is that everything about the celebration is "bride's choice", of which the modern version is that it's all up to the couple. That overrides everything else. 