Mine is pretty short because it's only about the non-routine stuff:
- passport + passport card + visa
- make travel notifications for credit cards (seems less needed these days)
- chargers + outlet adapters
- download maps for areas in Organic Maps, bookmark important places (don't trust Google Maps' offline maps)
- write down confirmation/reservation numbers and important phone numbers
- remove pocket knife from carry-on
- headphones + earplugs + eyeshade
- spare glasses (even an old pair works. yes in Asia you can get new glasses in less than an hour)
- do you need swimwear, sunscreen, or a headlamp?
- lacrosse ball to roll out knots (very personal, but 10hr flights in a cramped economy seat can put a strain on one's back, esp as one gets older)
Again, this is my personal "perennial" travel checklist. It's written from my experiences of having a girlfriend break my glasses while needing to drive the next morning, and forgetting headphones for overnight bus rides.
Similar to susam, I've also started keeping another trip-specific checklist (e.g. any items my in-laws want from America, or bring 98% DEET for SE Asia). These get deleted after the trip.