I would love to see an icon added on each building (minus walls) in your village map that indicates whether or not it can be upgraded. Something very simple, like a little green up-arrow hovering just above one corner if there is an upgrade available for a particular building and you have the resources available to do it. Maybe have the arrow grayed out (but still present) if you don't have the resources. This would save the time it takes to click on each building in turn scrolling through them all to see which ones need to be upgraded and which don't.
