Unbeknown by travellers but frequented by Vientiane locals, the Tha Ngon floating restaurants is a quintessentially Laotian experience that you ought not to miss. Get a personal houseboat that's fully staffed and enjoy a traditional meal - take note that it can be quite spicy. Sing karaoke, sip BeerLao and relax along Mekong river without the horde of tourists. Be warned, though: you have to hire a restaurant by noon, as they are snapped up quickly.
To rent a small floating boat for up to 10 people costs just 100,000 kip (US$12) for a full meal. A larger boat can seat up to 16 people, but it is normal for an entire boat to only be occupied by a handful of people.