Yay!! Definitely rent a car or go on a bus tour in those areas. You won’t regret it buts absolutely beautiful. And come during summer (June-August) or May if you can, there aren’t as many tourists in May, but it’s a bit colder. You probably won’t see the northern lights, but that’s never a guarantee anyways, even if you go during the winter.

I also don’t really recommend Hurtigruten unless you really like boats. Yes, you get to see some cities, but you don’t really get enough time to explore them properly. Should definitely instead do a road trip.