Wedding cakes and miniature cakes are covered in marzipan or chocolate ganache and sugar paste, I find it helps keep the freshness of the cake and adds an extra taste dimension.
Combining the flavours of cakes in each tier is a great idea, why not serve the cake as a desert at the wedding reception. If some of your guest's have food intolerances you can introduce mini cakes or one of your tiers can cater for their needs.

Here are a few ideas but if there is something else you have in mind then just let me know,
there are no limits!

• Vanilla bean sponge with vanilla buttercream and raspberry conserve
• Luscious lemon soaked sponge with lemon curd buttercream
• Rich Belgium dark chocolate cake with a chocolate ganache buttercream
• Rich Fruit cake soaked in brandy
• Moist carrot cake with a orange buttercream
Choose from lot's of exciting fillings, from baileys chocolate ganache buttercream to cherry preserve with a dash of cherry liqueur.