i've been playing around with decorating cupcakes and biscuits with fondant. i've to say that i like fondant best on vanilla cookies. for me, the crunchiness of the cookie goes really well with the sweetness of the fondant.
i enjoy decorating cookies with fondant more than decorating cupcakes. in my opinion, simple cookies becomes very elegant when decorated with fondant whereas fondant decorated cupcakes are just cute. but i think cupcakes are best swirl with lots of soft frosting on top.