I've got some plans but would welcome any suggestions on what I might be missing
So far
4 nights Belgium (combination of Brussels, Antwerp and Bruges)
1 night Cologne
3 nights Munich (incl Salzburg visit)
3 nights Vienna
1 night Venice (been loads before)
2 nights Naples
4 nights Ischia
Then, we've got 11 days to get to Stockholm going via Strasburg, Hamburg and Copenhagen
Doing Oslo after Stockholm
exciting times
DO take time to do Copenhagen justice. It's a great city to just walk around ... and, tourist trap that it is, sitting outside a bar/restaurant on Nyhaven on a nice day, is hard to beat.
Stockholm is mega expensive, but a walk around Gamlastan is an enjoyable hour or so. A circular around Ostermalm taking in food/drink in Saluhall is a good diversion. This is a great little excursion for a day https://www.visitstockholm.com/o/fjaderholmarna/
Did I mention that Stockholm is expensive?
Slussen/Sodermalm/ Djurgarden are other places to check out.
When I go, I walk everywhere that doesn't involve crossing water.