I went there earlier this year, I'd skip Vientiane it was boring ass. Luang Prabang was much better, much smaller, more relaxed. Stayed at a place called 3 Nagas which was pretty nice boutique style hotel, I'd recommend it. There's another place in Laos that's more popular with backpackers and probably has a more interesting nightlife, can't remember what it's called though

I never made it there.
Are you going to checkout Cambodia or Vietnam? both seemed more happening in terms of nightlife than Laos. Of course Thailand has plenty going on too.