I've been doing a trip every year without my wife, who I've been married to for more than 30 years. (Pre-Covid, that is.) Some were a week long in the California Sierras, some are more than a month somewhere in the world. Pick a country (and I have a long list), research it and make a very detailed plan going from one end to the other, and then make all you can to make your plan obsolete... It may sound weird, but I do vary good planning based on information available on the Internet. But when you go somewhere, anywhere, make sure you mingle with the locals, ask things around and very often you have a better place to go to, better food to try, etc. THAT to me is what makes a trip. I stay at hostels; not too accepted in Europe at my age, but South America, Asia and Africa are fine. If I stay in hotels, I see myself in the mirror; not much to see. But if you are at a hostel, you meet people, old and young, from all walks of life.
My advice to those who haven't tried that yet - do it!
Some useful details on travel - check out how you can buy airline tickets to one place, return from another. Since 2011, airlines dropped the price of multi-city tickets dramatically. Before that these were treated as first-class tickets, round-trip was far cheaper. But since then, I have always found a multi-city ticket that's cheaper than a round ticket to a nearby place, every time! And it doesn't depend on the continent - Europe, South America, Sout-East Asia, Africa...
I've been itching to go for two years, but Covid hit... Next year I'm going abroad again.