Place cards for 1st b-day party?

DS's 1st b-day party is not formal...it's at a VFW on a Sunday afternoon. I am making place cards b/c I am having a lot of friends and family with kids and I want to make sure everyone is sitting with someone who's kids are in the same age range and will have a good time chatting with each other (DH thinks I am insane for even thinking about this stuff...but I do...I want people to have a good time and feel as comfortable as possible).
Anyway, being it is informal, do you think I need to write "Mr. and Mrs." or can I just write "John and Jane Smith"? I am thinking John and Jane.

Re: Place cards for 1st b-day party?

First names would be more appropriate. We chose not to have place cards because we didn't want it to end up like our wedding where, invariably, someone would get upset as to where they were seated It worked out for us to have "free seating".