I tried to figure out the bus situation from Luang Prabang to Vang Vieng but little was available so I thought I'd post about my experience today 3/1/2012. After asking around in LP I got many different prices, the cheapest being 115,000 pp for a air con mini bus from your guest house. I was told I could pick 800 or 830 as departure time with a 6 hour drive. Got picked up on time but by the time we loaded up in a different mini bus and left the bus station it was almost 10 and we made many stops along the way. We didn't arrive until almost 1700. Plus yes the bus has air con but the driver wouldn't turn it on sobit was windows the whole way. First half is rough I wouldn't go on a full stomach, I had read this but I have a strong stomach so I didn't listen and I felt half for first 2 hours.