Travels in this area are really best done with your own vehicle, hired in either Moscow or Vladimir. But if you're using public transport, take a Sapsan train to Vladimir in the morning, spend the day checking out its attractions, then take a bus to Suzdal, 36km away.
A scenic road continues from Suzdal to Ivanovo (79km), where you can change for a bus to Plyos. The bus travels along M7/R600 for another 51km until Privolzhsk, then Plyos is 17km to the northeast.
From Privolzhsk, the road goes along the Volga all the way to Yaroslavl, passing Kostroma. The 280km Yaroslavl–Moscow section of the M8 is a fairly modern highway, with Rostov-Veliky, Pereslavl-Zalessky and Sergiev Posad breaking it into four more or less equal sections. Fast trains between Yaroslavl and Moscow stop at Rostov-Veliky, from where you can choose to continue by bus to Pereslavl-Zalessky and Sergiev Posad.