Around 5500 surfaces, 1700 sub surfaces, 1200 shading surfaces and 600 zones, which for the most part is zoned core and shell - it was also brought through via gbXML so there are some unwanted shading devices but most of them are accurate. It's a very non-uniform geometry with many varying glazing selections in each zone and lots of shading devices.

Is there a reason the surface properties aren't exposed when rendering by construction? I don't see much benefit in the construction properties being shown when you click on a surface because generally there aren't that many constructions. It's a great feature to ensure construction assignment is accurate, but it makes correcting misassignments very cumbersome having to toggle between different rendering views. Feature request?

I see your point, doesn't allow for quick construction assignments. One thing to consider is to clear out all of your hard assigned constructions (Remove Hard Assigned Constructions user script), and then rely on a building wide construction set to define what constructions are used for exterior walls, exterior roofs etc. You can also do this by story and by space type, and then where you need to can override as needed for individual surfaces.

If you expect to re-import updated versions of this gbXML later on another option is to clean up the constructions in the source gbXML file.

I ended up using the first path you suggested and was able to coordinate glazing selections based on window areas and a few other things to get the bulk of it done.

Going forward I'll probably post process the gbXML to create a construction for each unique <CADObjectId> (minus the actual ID number) to allow for the assignment to be performed from within Revit by using different family types.