Which Lens to Add?

My kit is the  OMD, the 12-35, 35-100, 75-300 & 45 (1.8)  I do a lot of travel photography which frequently involves architecture.  I am considering the Rokinon 7.5, the Panasonic 7-14 and the Oly 9-18.  Since I have the 12-35, do I need something other than the 7.5?  In a situation where I needed the UW, wouldn't the 7.5 suffice?  Couldn't I simply zoom in by taking a few steps?  What uses would I have for the long end of the 7-14 that aren't covered by the 12-35?  Thoughts?

Taxjam