I like Kevin’s ideas. While this one is a bit over the top it seemed pretty practical.

Step 1: Create a filter that auto-responds to all unopened emails > 14 days old w/the following message:

Your email (below) is now 14 days old and has not been opened.  To minimize email buildup your email has now been placed in the archive.  Should you still require a response simply respond back and you’ll automatically be added to the priority queue.  Thank you.

Step 2: Setup another filter that looks for the text "Your email (below)", this will catch the email responses back to you from those still requiring your response.  Filter these into a special folder you check and respond to daily.

My other big one is to create a CC folder and a rule that places all email you are copied on in it.