The problem is that even when I think about things I'd like to add, such as mass combat or rules for building keeps and other structures or businesses I remember that even when we had those rules I rarely used them. Heck, I bought Colville's Stronghold Builder's Guide and it's collected dust ever since.
I would probably get more mileage out of more templates for "upgrading" monsters quickly, we have a couple but I'd like more. While I don't want a repeat of skill challenges from 4E an expansion of the chase rules and some ideas on how to run businesses and the like. I want to avoid the "non combat should be handled like combat" feel, but ideas on how to handle the odd cases would be appreciated.