no way is that too geeky! I think it's top idea if it's you.
For your invitations you could have Mario battling one of the enemies and the Princess in the background....then when they get to the wedding there will be the two of you on the top of the cake....happily ever after....
cover the tables with vines......oooh and redfortune cookies to represent those round redflowers...then the guests could take them home.....