My grown son and I are flying into Stockholm on September, staying at an Airbnb for five nights and exploring Stockholm, doing something else we haven’t figured out yet and then flying out of Copenhagen three days later. Uppsala, Dalarna&Falun, Cosby, and Helsingborg.are places we’re interested in visiting. I know it’s too much, but any thoughts about a good (scaled back) itinerary? Thank you!
Cosby?
It's your trip so you you need to decide what you want to see and do. Since you haven't told us anything about what you're looking for it's hard to give advice.
Concentrate on Uppsala as one day trip is enough while staying five nights in the capital. Helsingborg is within sight of Denmark and you could take their 20 minute ferry across the sound and then a regional commuter train down to Copenhagen.
Cosby...? Yes... Now I remember... "The Cosby show was brought to you by"...