To organize such a demanding trip in terms of cost and length, in addition to the period, you need some basic information:
- Time available.
- Latitude to which you want to go. In your case I understand you would get as far as Kristiansund (northern end of the Atlantic Road).
- Personal interests. Only nature or also history and architecture? Hiking and trekking or (like us) are you no longer old enough for demanding walks?
In one case cities like Oslo, Kristiansand and especially Bergen are worth a visit.
In the other places not to be missed are the Prekeistolen (4+4h excursion) and Trolltunga (maybe a dozen hours round trip).
I would always refer to one of the two Scenic Routes sites:
Both list them from North to South.
They are all passable without difficulty even by medium-large motorohmes. With some exceptions.
The Gamle Strynefjellsvegen (I think it means Old Stryn mountain road) which if nothing has changed includes about twenty kilometers of dirt road.
Aurlandsfjellvegen, the climb from Laerdal for the first nine kilometers is very narrow and almost nightmarish.
The Hardanger has some narrow stretches but nothing insurmountable.
From Laerdal consider going to Flåm.
From there it is possible to take a small train to Myrdal and back.
For those who wish, there is the possibility of making a complete tour that requires a little less than the whole day.
From Flåm to Myrdal Train
From Myrdal to Voss Same Train
From Voss to Gudvangen Bus
From Gudvangen to Flåm Motorboat on the Nærøyfjord (Unesco)
Notes: from disembarking the ship, return to Flåm by shuttle bus).
In Geiranger, don't miss the pedestrian mini-cruise on the fjord.
If you come from the North (so-called Eagle Road) then continue on road 63 and go up to Dalsnibba, unsurpassed view of the fjord (toll road).
Further south, you'll find the Ryfilke and Jaeren routes, perhaps less spectacular but both worth traveling.
Others if they come to me.