What to do 3 days in between Stockholm & Copenhagen? Visby, Gothenberg or Oslo???

Had decided to fly vs ferry (is it just a big party?) as have airbnb already in Stockholm but airfare tripled for 9pm flight. Still OK for 7 Am next day. Fly? Ferry? What to see in Helsinki Finland for 1.5 days too

Take ferry. Not one big party. Best way. Don’t fly.

I much prefer the ferry to flight when traveling between Helsinki and Stockholm. You get to sail through the beautiful archipelago as you come into Stockholm. It is less expensive too if you take into account that you save the cost of a hotel night. Weekends can have more of a “party” atmosphere but I’ve never had trouble sleeping on the ferry. Avoid the cheapest C class cabins that are below the car deck. I prefer eating in one of the restaurants rather than going to the buffet.

What month are you visiting? Accommodations can be hard to get in Gotland in the summer so Visby might not be an option at this point.

Well, I definitely would not choose Oslo to visit between Stockholm and Copenhagen because it's somewhat out of your way. And while it's a nice city, I think that you'd be better off visiting Visby, which is supposed to be absolutely beautiful. I have not been there, but it's pretty much in between the two, and it's on an island as opposed to just going to another city. You'd have a different experience there.