Good morning,
My tentative plan is:
Stockholm: 2 Days
Helsinki and Porvoo: 2 Days
Overnight Train to Santa Clause Village (1 day for the kids) and return that night to Helsinki (we are not big on out doors/nature activities when in northern Europe as we live in rural Canada).
Tallinn: 2 Days
Riga: 2 Days
Vilnius - Trakai Castle: 2 Days
Gdansk and area: 4 days
Visby, Gotland: 3 Days
We also plan on stopping into places such as Kaunas and Parnu.
And looking for a night stop between Vilnius and Gdansk.
With the family we have booked a hybrid rental. and using overnight ferries and train (Santa Clause Village) to maximize our days adventures.
Thanks and have a great day,
Nate