I keep thinking about the most efficient way of doing this ... maybe someone else will have suggestions, too, or can critique my thoughts, but if you don't already have plans set, I'm thinking you should fly into Bergen and start there. If you want the Norway in a Nutshell highlights, you can take a train from Bergen to Myrdal and pick it up there. The Oslo-Myrdal train ride is five hours and not very scenic, whereas it would be two hours from Bergen to Myrdal.

When you get to Flam from Myrdal, take the express boat to Balestrand (another option would be taking a boat straight from Bergen to Balestrand) and a boat/bus to Fjaerland. Spend a night in Balestrand and go back to Bergen.

Fly from Bergen to Trondheim and take the train from there to Oslo via Alvdal and Hamar.

You could figure out where you wanted to spend your nights, but depending on flight times I think you could do this in five days, and you go to Trondheim.

I'm sure you know Bergen has Grieg's summer house Troldhaugen and Ole Bull's house on Lysoen is not far away (kind of over the top, but it's a nice island to walk around, picnic and swim off of).
http://delius.the-mill.co.uk/pics/pictures/4.jpg

Have you seen pictures of the Tronsberg Library? Not that you have room for more, but I thought that might interest you since it's contemporary and your interests don't seem to be running toward stave churches.

BTW... I hope you'll do a trip report on this. I haven't been to the Glacier Museum or some of the stops on the rail line from Trondheim-Oslo you're goint to hit.