Honestly; preikestolen has been done from all angles and then some. Kjeragbolten is a little bit better, but Trolltunga is much more in demand, since it is less accessible. If he goes up there, I would also try to get some shots in the old factory town of Odda. And Rosendal is fantastic, especially in spring. Several songs have been written about the fruit trees in Hardanger.
In Stavanger, I would look to the sea, that is what the locals do. It is the oil capitol; he should be able to get some good industry shots, the oil museum might be a good start. There are ferry boats and high speed passenger boats going to all directions from Stavanger, one of them all the way to Bergen. Would definitely recommend doing that.
Kvitsy is a tiny municipality a short ferry trip from Stavanger, places like that are full of photo opportunities.
Honestly, I've only been in Stavanger city once, and really didn't care for the town. As you might have guessed, I prefer the fjords further to the north.
