If you want to harden up your legs for Loei's national parks, Phu Bo Bit gives you 600 steep steps to practice on, and rewards your effort with great 360-degree views of the town and the surrounding mountains. It's a decent climb, but can be done in half an hour or so each way. The park is about 6km from the town centre along Rte 2138. You can get a túk-túk there and back for about 250B, including wait time.
Many locals come up here at sunset and stay till after dark to see the lights of Loei. Needless to say, it's a popular photo spot.