To get a year-long, multi-entry Non-Immigrant Type O visa based on marriage to a thai from the consulate in Savannakhet you need
the original marriage certificate (if married in thailand it's the one with the rose border)
copies of:
front&back of the marriage certificate
front&back of your thai wife's i/d card
thai wife's house book listing
data page of your passport
lao visa and entry stamp
(you sign everything with your name on it and your wife signs everything with her name on it meaning you BOTH sign the marriage certificate copies)
you need 2 passport sized photos and the filled out application along with 5000baht. You turn in your application one morning before 11:30 and you pick up your passport the next afternoon after 1:30