Latvia: went to Riga in the mid-2000s and ended up drifting into a crowd in a square - thought it was an open-air gig (there were bearded blokes in viking outfits chanting on a makeshift stage), but turned out to be a fascist rally. An armed policewoman with scene girl mascara totally lost control of her horse, which was exciting, but I left soon after someone asked me for a fag and then got tetchy when he realised I wasn't a native. Saw a few skinheads in paramilitary gear who made our homegrown "Oi! Oi!" ones look like teddy bears. They have a Museum of Occupation where it's explained that Latvians hated the Russian occupiers so much, they greeted the Nazis with open arms - maybe that's why I saw TUPAC and a swastika scrawled on a bridge. The sky was a really beautiful sort of blue you never get in the UK.
Lithuania: wasn't here long, they have a cool Soviet fighter jet graveyard.
Estonia: went as the guest of some government maritime trade initiative. At the time (2017?), they were trying to attract overseas IT bods to bump up their tech sector. You could get a 3-bed flat just outside Tallinn for 100,000 Euros and loads of tax discounts if you were immigrating with an IT start-up. Tallinn's nice, old taverns, but I liked the island Saaremaa too. On the last night, one of the govt reps got pissed and started asking me loads of questions about English football hooliganism, he was fascinated. I got a bit drunk too and accidentally called Estonia 'Latvia', twice, which really pissed off another of the reps - it was explained to me after (in a strip club, which one of the reps insisted we went to at 1am) that many Estonians view the Latvians as educationally subnormal.
Does St Petersburg count? That was the best.