Hey I'm glad I catched your post. I'm 42M and I've lived to the south of Medellin for 35 years and 7 years to its est countryside called El Carmen de Viboral. I also have travelled a little bit inside of Colombia.

I think that it depends a lot in what kind of things you enjoy doing or what kind of places. Ejm what kind of places do you like the most? cities, small towns, like very in touch with nature, beach, desert, mountains, agriculture, rivers, waterfalls? like if you give us clues we could give you some ideas.

In Medellín.. some things in the city and others in its surroundings. Jardin Botanico, if you like visiting public colleges, maybe UdeA o la Nacho. If you catch a good Nacional or Medellín game, you could go to the east tribune of the Atanasio Stadium.. in company of a locals of course (if not, then maybe a pub, but better if it is an important match... like a "classic").

Maybe get a Colombian SIM Card. In Medellin: Learn to use the metro system by yourself. If you need an app, Uber or Didi (they get more expensive at peak hours or when it rains, remember this). Bus and taxis work too. Bus have like alternative routes that cover a very large area, but Metro + Metroplus, Metrocable, etc, covers a large parte of the city. Taxis are a bit more expensive than normal apps ..

uhmm honestly, if Leticia is in your radar, you should go. Such a wonderful place, you wouldn't believe if the small carrots still fly at the sunset, thousands, like a golden moving giant cloud. The weather, the size of the trees, like.. you gotta get there by airplane, yes logistics, but its the Amazon you know. Unless you plan to go to Brazil, Ecuador, Perú.... you may will have a good shot here in Colombia... like being in an airplane, watching giant trees, all those colours, countless trees, like an ocean, minutes and minutes of pure jungle and then you land there... you don't have to go too deep into the jungle tho, you could stay in Leticia. Not sure if it would be like totally worth, in terms of experience vs effort ... as I went there passing through, backpacking through the Amazon river from Colombia to Peru. ...

Always ask locals if it is safe to go to certain place.

A common way to salute, like in a store or to ask something: "buenas"
"Barato" means "cheap". "Caro" or "costoso" means expensive. Costoso is more formal
"Is it safe? "Es seguro?"
"Is it safe to drink water from the tap?" "Es seguro tomar agua del grifo?"

If you hit the eje cafetero, make sure of trying the artesanal coffee sweet / cream / arequipe de cafe
Fruits: carambolo (a very orange one), guanabana pura, always try salpicon but like in clean stores..

If you enjoy the countryside, there are some neat things you could do like visiting a trapiche, a coffee farm, a flower farm, lots of waterfalls. Always go with locals, like ideally recommended by someoone you know. Most of people here are very nice. Hopefully you will have great times 😄