So I didn't bug SWMBO enough to get my passport out of the safe-deposit box.. and I finally got off my duff and got it out myself, about 10 days before a planned Canada trip and found it expired - last month.
ZOWIE! That was a costly mistake. The basic government fee for renewing a passport quickly is $170. That's bad. Worse is having to use a passport service to do it for you. Turns out that the only quick way to renew a passport is to visit a passport center. Those are located in major cities that have a "Federal Building". No more going down to the post office.. And to go to the passport center you must make an appointment. I called all the major ones within 400 miles of me - and the soonest any could offer an appointment was a week after the trip was going to be over. That wasn't a working solution.
So - I went to a passport service. These services are authorized by the government to process passports for people, and somehow they have access to getting it done quickly. For a bit under $250, I should have my new passport next Tuesday. Company seems very efficient, got excellent writeups in lots of major travel and business publications, but - it appears their cost model is based on a business paying for an employee to get an expedited passport, and for the average Joe Schmo that is a lot of money.
Lesson is - plan to start the renewal process at least 2 months before you need the passport. It will save you a bunch of money that could better be spent on the trip.