I think the length of time you have will decide how far north you go. Last year we spent 2 months doing a "round trip" via Rotterdam, Germany, ferry to Sweden, north up the Baltic, into Finland then Norway.
First east to the Russian border, then west to North Cape and south via Alta, Tromso, Narvik, Lofoten Islands and Bodo. Then all the way down the coast to Trondheim,Kristiansund, Alesund, and into the fjords and mountains north of Bergen .
From Bergen on south via Stavanger, Kristiansand and right round the south coast with a side trip into Telemark, and up to Oslo.
Then south to Goteborg and Malmo, bridge/tunnel to Denmark, south on the islands to Rodby and ferry to Puttgarten in Germany, and finally back to Rotterdam. About 7000 odd miles.
Even then we did not see all we wanted to see!