Pretty much everyone will sell you a tour to the falls, for good reason. While not the highest or the widest or other superlatives, it is pretty and fun, especially on a hot day.
You can climb right to the top, which is a steep 20mins, or just lounge in the pools and perfect your best jump/dive shots from the tree in the middle pool. We were there in wet season so the falls themselves were in spectacular full flow. The asiatic black bear sanctuary was a cute added bonus that we were not expecting. We arrived at feeding time (12.30) so got some good shots.
Outside the falls is an area with food stalls and overpriced souvenirs, which we skipped, but you do have a range of lunch options if you are hungry.
We went in a private car with our guesthouse owner (Mr Vong of Lao Wooden House), which meant air conditioned comfort on the 50mins (ish) drive out of town. He waited while we explored and had provided towels and water, as well as stopping whenever we wanted for photos on the way home.
At 250,000Kip (for two not each) it was more expensive than going by Sangthaw but also more comfortable. We initially considered cycling, but its a fair way and windingly steep uphill in parts so not for the amateur peddler. More