take your time in Stockholm for a city tour and the changing of the royal guard at the castle at 12. I´ve never seen such a spectacular guard changing in other cities ín Europe.
And walking through Stockholm is wonderful. Small streets with nice shops with specialties from Scandinavia, like glass and special designed jewels. You will love it.
I dont know if you will visit Helsinki too, its also wonderful and Tallin in Estonia.
Enjoy your cruise, we did it last year with the Jewel OTS,