Vang Vieng town is surrounded by limestone mountains and many magnificent caves. The most popular one is Tham Jang cave. Boat riding on Xong river flowing around the high limestone cliff is an unforgettable experience for a traveler. Nam Ngum Dam Lake formed from the building of Ngam Ngum hydroelectric dam is 250 square kilometers large and dotted with many islands. The lake and the surrounding high mountains are an amazing view.
Boat riding in the lake is possible.
Or you can directly go into Laos from Nong Khai, Thailand's border city with Laos. There are daily flights to Vientiane from Bangkok by Thai Airways and Laos aviation. Below is a sample tour itinerary to Vientiane starting and ending at Bangkok central train station. Cross the border and arrive at the Laos side. Check in hotel and lunch.