There are no many organized tourism related activites in Pak Lay yet and some visitor will find it boring here. On the other hand, Pak Lay is nice provincial town to stay for a day or two and walk around if not too hot. It is rural district capital. In the main streets there are several colonial buildings left in typical Inodchina style, large footbal ground, temple, market, shops and restaurants with mostly local foods. A lot of new houses has been built recently throughout the town as well as guesthouses, restaurants and hotels. To have good Lao meal it's good idea to look for restaurants in the street west of Market; however most foreign visitors will be eating at restaurants further from Jenny's GH which have terrace upon Mekong bank with nice views (but foods we ate there several times were not that nice).
In the afternoon there are plenty of things going on next to and in Mekong river and it can be fun watching kids go tubing downstream or teenagers and adult men playing kataw. Even walking through temporary vegetable gardens, sandy 'beaches', swampy areas, buffalo pastures and large stones on the river bank in dry season is relaxing and it feels good to be there in Pak Lay and to enjoy its remote quietness. Having eyes open will keep you busy.
Unfortunatelly I was always passing by these rice terraces by 'public' transport without taking any photos but they looked really nice with hills and forests covering slopes around and farmers taking care of the fields. They're about 15-20 km from Pak Lay towards Thongmyxay district and are best visited by bycicle or motorbike or whatever you can rent in Pak Lay. These terraces are one of the nicest sceneries in Pak Lay district in terms of cultivated landscape but if you've been to Yunnanese ones they can't be really compared of course. If you stay in Pak Lay for a day or two and manage to rent your own transport you'll have nice trip off the usual paths. Antoher possible way to get there would be asking the pick up driver on the way to TMX to drop you at the terraces but then you'd probably have to hitchike back to Pak Lay.