If you still have some energy and time and are up to some offroad adventure, you may do a detour to Ban Phakheo Village. Normally, 2 days hike to that Hmong village, including a visit to nearby Jar Site 52 and Tad Ka Waterfall costs way over 100 USD when organized for a group of 1-2 people from Phonsavan. I believe it’s way too much for a hike in Laos so why not go on a motorbike independently? Look for “Turn-off to Tad Ka Waterfall” in Google Maps and follow the dirt road for about 1,5 km when you will have the junction to Pakheo. Turn right and just follow the dirt road passing by some other small villages on the way, until you reach your destination. The road is in decent condition and can be easily done on Honda Wave or similar. The panoramic views around the mountains are amazing and the location of Ban Phakheo is superb too. It’s well worth visiting here independently, even though the hike must be nice too