I took the train back and forth from Bangkok to Nong Khai. The first night started about 8 pm at Hua Lumphong and I slept on the train. I got to the border easy and early enough to go straight to the Embassy. Then 1 night in Vientiane and pick up the visa on the second afternoon. Then back to the border and the night train back to Bangkok that night - slept again. I loved that trip and the train was less than 1000 thb return.