First, it an interesting thought to form a group. Especially for those not familiar with what surprises can be experienced weather-wise in Norway. Second, knowledge of national rules & language will help (although almost everone speaks English), as well as knowledge of the weather. We will be crossing mountains whichever route chosen, and it may be a different task compared to Spain.
Personally I would choose the Gudbrandsdal route, crossing the Dovre/Rondane mountains: Beautiful sceneries and lots of history.
Finally, if any forum member visits my area, I would like to be contacted!
Edit: As Doug correctly informs, accomodation may be a problem (longer days, not always well equipped, few beds). Staying in hotels/eating in cafes along the way will be out of my reach by far due to prices in Norway. That is why I would not walk without all I need to be self-sufficient, but will welcome a bed anytime! (Old soldier instinct kicking in..)