You can do some window-shopping at Nakhon Phanom Walking Street during your visit to Nai Mueang. Take in the museums while you're in the area.
You can learn about the history of Nai Mueang with a visit to Naga Monument. Take in the museums while you're in the area.
Though Nakhonpanom Ratchanakarin Psychiatric Hospital might be what brings you to town, perhaps you'll have a chance to explore more of Nakhon Phanom while you are here.