Hi, M.
When I travel by bike, I prefer to stay in hotels/motels/pensions. I think we are in similar age groups, and being 48, if there is a camping site and a hotel across the street, I'll go to the hotel.
Being that said, I usually leave the bicycle in the hotel (some hotels allow me to park it in the room, and sometimes they have a secure room for storage). Then I go to the museums, restaurant, walk around town w/o the bike.
One one of my early new trips (like you, now the kids are old), I remember taking a U lock and never using it. But again, I mostly stay at hotels.
What I carry now is an emergency bivvy bag in case I don't make it to my destination and I have to sleep on the side of the road, which happened to me a couple of years ago on a trip to Argentina (if you want to read about it, I made a short essay here: https://medium.com/blueinsight/aloneness-without-despair-f4d4fda5aa37 )
What trips are you thinking about doing?
Pablo