I find the more commercial buttercreams are too sweet. However, a homemade or artisinal can be delightful. I'm personally very fond of flavouring mine with cardamom, over a champagne sponge with a layer of pomegranate compote. So yummy.
I personally love dark fruitcake but have no use for light fruitcake. I think one of the most entertaining changes I've seen here in Canada in wedding cakes is that as people started more and more to actually have a non-fruitcake cake (whether it be chocolate or lemon or what have you), a cottage industry in fruit-cake wedding favours grew up.
You'd go to a wedding and eat the wedding cake. Then there'd be a basket of pre-cut-and-wrapped pieces of fruitcake wrapped in plastic wrap and a paper doily. (See this picture here:
http://www.jessicazaisblog.com/wp-co...1/08/jones.jpg - exactly like that).
I think they're falling out of favour, though.