350km north of Pakse is Thakhek, city mainly popular for the 400 km loop that you can make by motorbike. You can do it in 3 or 4 days depending on how long you want to spend on your motorbike each day and also the road condition. Travelling from South to North of Laos, I did not complete the entire loop, but the last 100 kms back to Takhek from the north are just on the main highway 13 so I don't think I have missed much.
