Southeast Asia. Still one (of very few) places in a tourist-dollar-mad world where you get the best value for your travel dollar.
Climbing Everest can be fun (not for me!) when you are 30, but after 65 those snowy hills can be a burden to climb. India is crazy. Pakistan and Bangladesh are no-go's just now. Myanmar too volatile.
Many tourist destinations in SEA are everywhere, and most are truly beautiful, but the costs, wow.
Bangforthebuck places abound in SEA if you think laterally and take the time to do some proper research. Google everything and everywhere.
Now for the important question - where would I go? Whee I go often. Malaysia. To be geographically precise, Sarawak, Brunei and Sabah. Well serviced, civilized cultures, people and comforts. Enough cultural diversity and travel adventures to keep anyone young at heart. Good bus services let you wander around and visit places I would have found difficult in the 1970s when I was younger, fitter, and more prone to wandering about with only a backpack.
When one is 60 or older, good comforts become more important. I use the Ibis and Novotel chain of hotels when I travel and find their rates are pleasantly affordable with a (free for the asking) membership - I'm not a shareholder, just a satisfied guest. Last month I was in Kuala Lumpur and coughed up A$45 for room and breakfast, A$37 in Melaka, Ipoh A$40, Kuching A$50 (hotels cost a little more in Sarawak) - 1980s US prices.
I've been here six times since 2014 and I'll be going back with my partner and friends in March 2019. We'll get around by bus and occasionally hire a car or a river boat for forays to more isolated areas. No orang-outans, that's now too travel-tour touristy for us. Treks, visits to isolated villages, lazy days spent traveling up rivers. Enjoyable and still quite affordable.
Fly to Kuching (the capital city of Sarawak) and explore for a few days. Prepare an itinerary and then wander around Sarawak by bus.
Whether you want to cuddle orang-outans or visit museums and art galleries, Sarawak will satisfy. Brunei is great for an overnight stay and to visit mosques, good food also but no alcohol. Sabah is a small paradise as yet largely undiscovered by the global hordes.
New Zealand is stunningly beautiful but has become tourist-cash-grabby, also overpriced for what's on offer. Australia is gorgeous, travel distances are vast (2500+ miles from Sydney to Perth, east to west coasts) and accommodation costs can be high - in our country town in Tasmania the two local motels are distinctly ordinary and want A$125 a night for their second-tier rooms. Otherwise, very friendly people, eye-melting scenery, excellent food and a brain-boggling array of good wines. Sydney is every US city rolled into one with a stunning harbor. Melbourne every country in Europe linked by trams (streetcars to you).
Wherever you decide to go, when one is retired with good health and a reasonable budget for travel, the world is your oyster. Make the best of it. I am!
Wherever you go, bon voyage.