Just like yourself, I had no idea what Plyos was, or why someone would go there. It is almost in the middle of nowhere in Russia, and has a very small population of about 2300 (according to wikipedia).
What you get to see in Plyos, is a beautifully scenic town by the river… old-Russian style.
I won't go into too much detail about this town, because there is not much in Wikipedia to learn about it.
About 120 years ago, a Russian painter from Moscow, Isaac Levitan, came across the hills of this town, and decided to start painting it all.
Upon displaying and selling his paintings back in Moscow, Isaac Levitan became incredibly famous, and the town of Plyos became a ‘Dacha' or Cottage resort town.
Russia has its own version of Christianity, derived from the Byzantine era. It's called ‘Russian Orthodox' because it adhears to a more traditionalist version of Christianity.
Plyos, most definitely, does not have a lack of churches, despite it's location deep in the province of Russia.
This is where Isaac Levitan painted most of his famous paintings. It's quite an unreal vista of old wooden monuments to long-dead priests, and a view of both the Volga river, and the township surrounding the entire area.
Upon arriving at the bus station in Plyos, a few furry creatures were walking around, without any hesitation to interacting with humans.
There is a lot of walking up and down hills here in Plyos. It can definitely be a relaxing destination, although anywhere that has tourists can't be particularly relaxing, in my opinion.
The town itself is scenic, and unlike anywhere that I've seen before. If you are pursuing a passion of painting, then this might be a place that brings inspiration.
Otherwise, just 3-4 hours here will provide enough entertainment, before you take the bus back to your main location, or your next destination in Russia.