Just checking.  With multi-entry Non Immigrant O visa can one leave Thailand, check into Laos then turn around at the Friendship Bridge to reenter Thailand the same day?  I do not feel comfortable doing this and may spend a night in Vientiane.  This would satisfy my requirement for leaving the country every 90 days.  I know I can get an extension for 60 days but need to go to Nong Khai anyway.  Thanks for any advice.

No problem to do a same day border hop to get a new 90 day entry from your non-o visa. People do it all the time without a problem.

Yes I have it down to a fine art out and back in in just under an hour. Most of that hour is queueing. Actual time in Lao 5 mins max.

I tend to get to the border at around 1130 always seems to be the quieter time. And as I can't be bothered to get USD I get a Lao visa in Khon Kaen Lao consulate in the way up. Save a great deal of time. Cost 100bht more but hey it's worth it.