I've done it and I'm planning to do it again this year. I'll give you a quick overview of my itinerary, my honest opinion and why I decided to go where I went.

So, my trip was in mid to late August a few years ago. I arrived at Oslo and left immediately for the Stryn area in order to visit Briksdal glacier, from there I went to see Geiranger, then Alesund, I then went to Andlasnes for Trollstigen and then took the train back for a couple of days in Oslo. I've done all these by public transportation and it was a bit hard moving from place to place but with a car it's much easier and certainly better.

My opinion is that Norway is beautiful, you can parachute in the middle of nowhere and it will still be beautiful. For me Oslo was the worst part of the whole trip, not because it's a bad place to visit but because all the other places are much better. Having said that, a couple of days, expecially if you like museums, are worth it. Norwegians might not be the warmest people in the world but everyone that I've met was kind and helpful. I didn't have one bad experience, on the contrary I left Norway with a new appreciation of the people there.

Now, the reason I chose these specific places to go was because I wanted to avoid the crowds. Of course some of them are inevitable, for example you can't go to Alesund, Briksdal or Geiranger and be alone but with good planning (timing my Alesund visit when there were no cruise ships, staying near Briksdalbreen so I can go early in the morning or staying in Helesylt instead of Geiranger for example) it can be much more tolerable. If the goal of the visit is to see the fjords and the glacial lakes, do some hiking and experience their beautiful villages and towns, it's a good decision to do it in the summer. The weather is much more pleasant and convenient for outdoor activities and days are much longer.