Hosting a Masquerade Wedding Reception?

I am trying to get ideas on how to host a masquerade for our future wedding reception. I want to have a nice normal wedding ceremony and to have the masquerade as the wedding reception theme. I am wondering if I should put on the invitation to wear costumes or just formal wear. We are going more for a present masquerade type ball, not 1700-1800 costumes or anything that would make our guests spend money. We will be supplying masks as the wedding favors. If you have any ideas on how to word an invitation or centerpieces, etc. I need help!!! LOL. Thanks