I wondered if you could maybe give me some pointers....
I need to find a suitable Norwegian surname that rhymes with first name of Martin.
There are so many nice Norwegian Surnames though which suits best is hard to decide.
People have different tastes/preferences.
I like the following....
Dalen, Sørensen, Bergseng, Johansen, Knutsen, Mikkelsen.....
there is more...
what would you suggest that Norwegians would say is a nice name to go with Martin??
All of the suggestions you have given are perfectly suitable. Martin is a common first name in norway and all the surnames you have given are also very common. Either in combination with Martin will be perfectly suitable.
In this link you can check how many persons share any given name in norway.