I decided to go with pistachio cake for my wedding cake. Now my question is what kind of filling to use and what kind of sauce to use on the plate. We chose pistachio pudding for the filling and a dark chocolate sauce on the plate. We are not feeling this combo and need some expert opinions.

I have never seen wedding cake plated with sauce but strawberry and pistachio go very well together.

Rose-flavored whipped white chocolate ganache!  Rose and pistachio go really well together.

I once made one tier of someone's wedding cake out of a rose-flavored cake (just a vanilla cake recipe, replacing the vanilla with rose water), filled with lavender white chocolate ganache.  The bride and I wondered if it would be a bit too bold, and therefore unpopular, but people kept coming back for seconds of that flavor.