We are planning on driving from Bangkok to the Thai Lao border (Vientianne) Does anyone know if there is a secure parking lot on the Thai side of the border where we can leave our car for a few days while we visit Vientianne?

Why not seriously consider taking the car with you.Makes it a lot easier to get around as you already know. Driving isn't much different over there just on the otherside of the road.Border formalities are a bit of a pain but not difficult and if you don't want to do it yourself there are agents in Nong Khai that will arrange everything (at a price!).

The last time I was in Nong Khai was about a year and a half ago and there was no secure parking at the border and I don't imagine that there is now since it didn't appear that anyone was interested in developing anything at the border.

My insurance agent strongly suggests NOT taking your car acroos to Vientianne. Falangs are selected for an insurance scam involving the police .

As there is no secure parking I would stay in Nong Khai for one night and find a hotel that will let you leave the car with them.

When I crossed at Mukdahan I left my car in the police station.

I realize this is a bit late for the OP. And, too bad no one from Nong Khai responded.

A friend who lives here in Korat makes regular visa runs to Vientienne. He usually drives and parks his car near the Friendship Bridge. He says there are several secured, covered parking lots in the area that charge about 40-80 baht per night. He says that most of them are near the intersection of the highway that leads to the bridge and the road to Nong Khai.

I've never done this myself.