Having been on the Scandinavia cruise in 2003, your concerns about the Stockholm and Oslo ports on the Grand Princess are well founded. The other cruise lines are docking at an industrial port right outside of Stockholm, and it's about a 20 minute walk to the main sights in Stockholm. Stockholm is a fabulous place to visit, and we were able to see a lot--walking tour of the old town (Gamla Stan) visit to the Royal Palace and then took a ferry to the Djurgården to the Vasa Ship Museum (which we enjoyed even more than the Viking Ship Museum in Oslo) and to Skansen. Skansen was my favorite. I guess my point is that I would not have wanted to miss an hour there, and the commute from the Princess port will cut into the time in the port. Stockholm is wonderful. We also had a very active day in Oslo, so I would have hated to have lost time there too.
And I wouldn't recommend the Dream to anyone--it's a dump (unfortunately, we have personal experience in this matter).
I hope that helps you with your selection and hope you have a great trip. If anyone else wants port info, we went independent (no excursions) in most of those ports and will be glad to pass along info.