[joachim]

If you have a 35 equivalent and a telezoom starting at 70 equivalent, I would not buy anything to fill that gap for landscape.   In the film days I used a Contax G set-up with 4 primes.   If I wanted it light I took a 35mm.  If I could take two lenses, I took a 35mm and a 90mm.  In case of 3 lenses I added a 21mm to the 35mm and the 90mm.  The 45mm didn't see much use and in particular not for landscape.  In my view a standard lens is most useful for people, in particular small children.

These days I use an mFT set up with a 12mm, 25mm and a 90mm.  The 12 is mostly landscapes, since I moved more into people I got a 25mm instead of a 17mm.  For landscape I miss a 17mm.   In my view a standard lens is close to useless for landscape work. 

My opinion on this.