Help! E-Party Place cards Question.

I am having my eparty brunch this weekend and the place we are having it at requires us to make a seating arrangements with place cards.

My question is...how do I put the names on the place cards?

Mr. & Mrs. ......
or
First Names with last name?

I am thinking I don't want it to be too formal, since its just my eparty and its a brunch. But I am not sure of what I 'should' do.

I am so confused right now! Please help!

TIA

Anyone have a suggestion?

I would do first and last names