Great post man!
I had a plan to built my hybrid bike (converting old MTB into city bike), the general idea was just to remove all suspension (especially the front, might change it into rigid fork) and change the drivetrain into roadies.
At the moment still looking some parts from aftermarket, and still looking for free time to actually doing it. Lol.
Should be a fun project! You could go for 700c wheels with beefier tires for comfort -- works great on old 26" mtbs, some even fit 700x38