Whereabouts do they live? My mum and stepfather live by the coast in Pembrokeshire, and are very similar in age to your folks. My mum is young, husband old and reluctant to do the kind of stuff my mum wants to do. Recently, they did an equity release deal on the house (3 siblings and I had to tell them we'd rather they enjoyed the money now and left nothing to us) and bought a camper. the result is that they can go off at the drop of a hat, crucially though, in comfort! Mum gets to see the places she loves, Dad potters about with the gas, water, electric hook-up etc because it's like an extension of his home. He sits in it if he gets tired, does the crossword, listens to the radio. Meanwhile, Mum is off climbing Snowdon or something with the dog, and comes back when she's done. Suits them both perfectly!! This week they're off to Scotland, but Dad will still be at home really, and Mum will no doubt be up Ben Nevis...
I asked where they live in case it's close - Mum would love someone else with a bit of oomph to play with!! She also goes up to London on the coach sometimes to see shows with some of her friends in the same situation. What is it with men of that age? Thinking about it, lots of her friends have husbands the same...