Second the Stockholm recommendation. Your 7 year old will love it! We took our kids when they were 1.5 and 2.5 so a little too young but we loved Junibaken, the Vasa Museum, Skansen (animals here), the Nobel Prize museum and the ABBA Museum. There's a playground around every corner with lots of cool things like in-ground trampolines, ziplines and large slides. We had a blast and it's an amazing city!
Ireland is also amazing and you could do the Dublin Zoo, Natural History Museum and drive to Fota Wildlife Park where they have lemurs and wallabies roaming the grounds. Then you could drive cross country to the west (about 3 hours) to see some beautiful landscapes - I would recommend the Cliffs of Moher, the Aran Islands (take a ferry for a day trip) and Ailwee Caves and Birds of Prey Center. They have lots of fun department stores - I would recommend Dundrum Shopping Center where there are several department stores, a great bookstore and a bunch of stores that carry children's clothing (Next, Zara, Monsoon, etc.) and I would also highly recommend the Avoca Handweavers store - they sell beautiful handmade items. And the food there is delicious.
We had a great time in Stockholm when our daughter was that age. There's the Astrid Lundgren (Pippi Longstocking) museum ( https://www.junibacken.se/en/ ). Skansen, is an open-air museum with miniature buildings and also a zoo. Also, pretty much everywhere you go has part set up for children with places to play. Even the parks have equipment like stilts children can check out. We were there in the summer, I'm not sure how it would be other times of year.