Most westerners, that is Caucasians and Blacks, Laotians call them "falang", come to Laos because they want to explore the unique culture, religion, history and natural scenery from the caves of Vang Vieng to rice fields of Champassak.
Nong Khai, near the border of Vientiane is a popular exit and entry point of Thailand. Many westerners who are long term residents of Thailand visit Vientiane every day from Nong Khai to renew their visa then they re-enter Thailand. While they are in Laos for a short stint, most of them do a bit of sightseeing around Vientiane.
Westerners who has visited Laos knows Luang Prabang because it is a popular tourist destination. There are more westerners, especially those from France and Europe who come to this part of Laos more than the southern region because Luang Prabang is a World Heritage Site, surrounded by french colonial architecture and many old Buddhist temples.
Many western backpackers visit Laos especially to see Vang Vieng because they enjoy many outdoor activities such as jumping in the river from swings, trekking, kayaking, climbing, biking, but the main reason they go to Vang Vieng is for the tubbing, which is basically floating down the river on a big tractor tube. Westerners also like to visit the several bars there where they stop for a drink (they love Beerlao).
Unlike 10 years ago, there are now many westerners in Laos and they are usually well behaved and friendly towards Lao people. There are some westerners who migrate to Laos and work in expatriate jobs and some are self-funded retirees, but most westerners in Laos are foreign tourists who are here for a few weeks, or they are briefly passing through for a few days because Laos is in the middle of five countries and they plan to see the rest of Southeast Asia.