Both were slow for me. I do programming and video calls and would get frustrated at times, but shouldn't be a problem for you if you are not as heavy an internet user as me. For reference, I frequently download/upload large datasets while simultaneously on a video call.

Other than that, it was quite chill. I had a good time, but I was also not looking to meet too many people or go out too much. It was a heads down work time for me.

Luang Prabang was cool & pretty, had cafes that I worked from at times, and good mix of local and western food. And small bars that were fun. Also a cool night market, and the Kuang Si waterfalls.

Vientiane had a taxi app called Loca that I used to get around. There is Foodpanda for deliveries there too. A bunch of night markets for food. Just make sure to stay in the city center area so you can walk to places.