Looking to see Gdansk,Vilnius,Riga,Tallinn and Helsinki. Have you done this and what are your suggestions?
We have been to all those places except Helsinki and they are great.
Consider Gate 1 Travel's tour that includes those places:
https://www.gate1travel.com/tour/central-europe-tours-12dclbaltich26.aspx
Also, Gate 1 has more tours of the Baltics. We have done several tours with Gate 1 and they have been excellent with low prices.
I went to Vilnius, Riga and Tallinn on a Road Scholar tour a few years ago and it is a fascinating region with so much history and things to see. The thing I really liked about Road Scholar was that we had a lecture in each city from a local expert on topics such as current events, recent history, social topics, etc. Definitely go there!
Last summer we were on a road trip through the baltics, so we did Vilnius, Riga, Tallinn and some in between - super nice trip. Helsinki would have been just a small jump, but we had no time anymore. Easily doable by rental, almost all people spoke English - well except for some old ladies selling fruit at a farmers market, but that worked by pointing fingers.