HELP Invite Question!!!

Ok How do I write the inner envelope?? I'm trying to do this right now.

Is it
Mrs. Laura Smith or
Mrs. Smith

I know that for a married couple I should write
Mr. and Mrs. Smith
What if the Mrs. is a widow or if she/he is single invite without guest

Argghht this is too confusing

The inner envelope does not have to be as formal as the outer. It is a personal preference. It can read either John and Sue Smith or Mr. & Mrs. Smith.

edited to post:
Addressing Wedding Invitations link http://www.topweddingsites.com/wedding_invitations.html

my understanding is that the inner envelope is more informal? so you can just write (sorry i forgot your example):
John and Laura Smith

etc..

Hope it helps :)

If you are doing formal then it would read:

Mr. and Mrs. Smith

Or Ms. Jones

I am finishing mine now to give to the calligrapher