Domestically (flying within Laos), you can go from Viengchan to most provinces, etc.
Viengchanh to Luang Prabang, Luang Prabang
Viengchanhto Houayxay, Bokeo
Viengchanh to Muang Sing, Luang Namtha
Viengchanh- Luangprabang ( LPQ )
Viengchanh - Xieng Khouang ( XKH )
Viengchanh - Houayxay, Bokeo Province ( HOE )
Viengchanh - Oudomxay ( ODY )
Viengchanh- Luang Namtha ( LXG )
Viengchanh- Pakse ( PKZ )
Luangprabang - Xiengkhuang
Luangprabang - Houayxay, Bokeo Province
Luangprabang - Pakse
Vice-versa...just adding to the list above...
Yes, it is true that you don't have to land in Thailand anymore, but I would say 95% of the time you will have to land in Souvannapoom International Airport in Krung Thep or Krung Thep International Airport.
The reason why I did not listed Lao Airlines flying in Laos is because that would be consider as a domestic flight. If I understood your question correctly the answer would be no. There are no Lao Airlines in the US or in the western world yet, thus you cannot fly to Laos using Lao Airlines from US, Canada, or European countries yet. You can fly using Thai Airlines, China Airlines, Korean Airlines, Japan Airlines, etc but then you will have to switch plane to Lao Airlines to fly to Laos.
China and Korean airlines are cheap and have extra room in comparison to any US airlines. United Airlines are the worse to fly internationally.
Don't ever get on Air Canada or Canada Airlines...oh man....oh man...haha Mexicana Airlines don't use it either...
Singapore Airlines are the best one! If you have extra cash laying around...book Singapore Airlines...haha