The three ex-Soviets all make intriguing destinations.
Armenia

I have been to Armenia once and had a wonderful time. I arrived by overnight train from Georgia, at one point sharing our compartment with a blind cat!
We actually arrived on Armenia’s Independence Day so we’re able to gatecrash a great party.
As well as the capital we explored several monasteries and the wine region. What a wonderful country.
Monastery Church, Armenia Geghard Monastery, Armenia Geghard Monastery, Armenia Wilbur Arrival By Overnight Train, Yerevan, Armenia From Batumi, Georgia Church Near Yerevan, Armenia Mount Ararat Through The Train Window Geghard Monastery, Armenia
Belarus

We stayed in the capital Minsk for four nights, arriving by long-distance train from Kaliningrad.
There was a strong air of Communism about the place. Minsk was afforded hero status by Stalin due to its efforts against the Nazis in WWII and Belarus remains very attached to Moscow.
We visited the state circus and the opera and enjoyed our time in the city.
Georgia
Minsk, Belarus
Georgia

I have visited Georgia twice and absolutely loved it both times.
Tbilisi is a wonderful city and the countryside is equally enthralling. A trip on the Kukushka train line was a particular favourite.
Metekhi Church Mother of Georgia Trinity Church River Kura, Tbilisi Bridge of Peace Mushroom Building Tbilisi to Baku Train -Provdonistas Await Passengers