Galaxy Pub is a live music club located on Samsenthai Road in Vientiane. Be careful as it has changed location and it is no longer by the Mekong river.
It is a chic place, with a dressed-up crowd and pretty girls (among which a few ladyboys though) that features live bands singing Laotian pop.
The entrance is free, and if it isn't too crowded the waiters will give you a table. I only had one lao beer for 25,000 kip.
It is a bit cheesy for my taste, but if if you want to meet upper class Laotian girls it could be an option (some of the girls could also be Chinese or Thai, I'm not 100% sure).
You can judge from this video I shot inside if you like it or not:
Galaxy Pub Vientiane
Every day from 8.30 to midnight.