I did this trip in Aug 2026 and I did it alone so the cost for two people would not be much more. I selected smaller rooms since I was traveling alone and the only room I recommend upgrading is the hotel in Bergen as it was a single occupancy room.
You can also do this in the reverse order from Oslo to Bergen.
This is a variation of the standard "Norway in a Nutshell" which is done by train. This is a fully customizable trip where you can add more stops, add more or reduce nights at each stop, and more. The variation is called the "Sognefjord in a Nutshell" where you take a scenic cruise/ferry through the fjords between Bergen and Flåm.