An example here of exposure blending is when I a pic without the filter (and a clear boat) and a pic with the filter (all moving objects smoothened). Two layers, and only expose the non-filter layer around the boat area.
We do that with buildings too, which is of course, a lot more work than just a tiny boat (i.e. masking along the outline of all the buildings) and then working on them. Once I was lazy and I used the Select Range function thinking no one would notice but night86mare commented on the halos around it. After that, I went back to painstakingly paint each building again.
With clouds, trees and other non-straight lined objects, it becomes a bit crazy... yes as mentioned, can try to split the top and bottom.
What's your workflow?