This site exceeded my expectations. Skansen is a really nice place, I'm not sure if there's anything quite like it in Helsinki - unless one counts Seurasaari, Korkeasaari and Linnanmäki altogether.
Also the cruise with Viking Mariella was nice. Stockholm's archipelago was as beautiful as ever.
Cows, chickens, sheep, goats, ducks, even peacocks - you name it, and this place probably hosts 'em all. The kid naturally enjoyed the visit, and luckily for grown-ups they'd also serve coffee or beer.