My wife is now 70 and has had road bikes rather than touring bikes. Her last one has to be, I'm guessing, over 25 years old. It is a Cannondale SR400. She's no longer doing triathlons and would like a sporty bike that's capable of being used for touring. I did the Northern Tier last year, but I suspect future tours for the two of us will be shorter - 7 to 10 days timeframe. She's done weekends in New England with me, but is willing to try something longer.
Firstly JW, my compliments to yourself and your wife to be still cycling and willing to consider touring at age 70.
I'm approaching 70 myself and can perfectly understand her wish for ride that is nimble and easy to handle. And the responses here are entirely predictable.
I'm a lifelong roadie, I appreciate bikes that ride and handle nicely. My first touring bike was a Surly LHT. It's probably the most over-rated bike I've ever owned, it was a slug to ride and I couldn't get rid of it quickly enough after only one tour.
Despite the entrenched ideas and disapprobation of the retro-grouches who typically frequent touring forums, I went my own way and built a titanium tourer with a carbon fork and integrated brakes/shifters. That carried me over many 1000's of kms, and despite dire predictions the sky didn't fall down - not even once (I still have this bike, but it now languishes unused).
Later I built a titanium bike with a Rohloff hub - but the Rohloff is probably even more over-rated than the LHT, and like the LHT it didn't last long before I got rid of it.
Currently to lighten the ride even further I've built up a Salsa Fargo (steel with carbon fork) and adopted a bikepacking setup. Now I'm looking around for a more versatile bike, one I can take on local bunch rides as well as bikepacking trips - just as your wife desires. BTW, if the the idea of bikepacking interests or appeals, take a look at this page.
Bikepacking 101The good news is - such bikes do exist, and in fact they are becoming more and more common at the same time as traditional touring bikes are disappearing.
They are called gravel bikes. They are built robustly enough to tackle unsealed roads without sacrificing ride and handling qualities, have suitably low gearing options and appropriate tyres for light touring.
A comprehensive list of such bikes can be found here:
Riding Gravel: BikeFinderAs you can see there are many choices. I've spent a fair bit of time looking into these bikes, and have picked the Norco Search XR as a likely candidate for my next bike. You can get a Search XR in steel, alloy or carbon, but my choice is for carbon with a 2X crankset.
Norco Search XR C3 Carbon is a mainstream material for bicycle construction, has been for decades now and the engineering requirements are well understood by the manufacturers.
I'm betting you are NOT going to set out on a self-supported world tour. You don't need a bullet-proof bike that will last another 20 years. Don't be afraid to make unconventional choices - disregard the naysayers here and get your wife the bike SHE wants.
A happy wife is a happy life.