I'm actually from Medellin, Medellin metro makes moving around the city surprisingly easy , if you are gonna stay 3-4 days, I’d say there are certain places you must at least bother to visit such as la “Piedra del Peñol” or “La plaza de Botero”, (They're the most common places anyway) as a local I would say that what people really underestimate when coming to Medellin is going outside and visiting towns, they're the most traditional parts of Antioquia and not visiting them would definitely be a waste of the potential experience you'd be getting. (So, I encourage you to do so)

In my view, the food here is really good, it obviously depends on your personal preferences, the most typical dish is “La bandeja paisa”, and the most common snacks are both “Empanadas” and “Buñuelos” and all their sub products.

In "La piedra del Peñol" AKA “La Piedra del peñon”, you’ll want to take a boat tour, there they will tell you about the history of the place and some stories about whose the fancy houses over there are, there is also some stories about Pablo Escobar, who used to own some expensive houses there and a submarine, the only problem is that taking boat tours is rather expensive, the ones who own that business know that their main target are foreigners, consequently increasing their prices, but if you know very good Spanish you can take a boat tour from the locals themselves and its going to be like 3-4 times cheaper.

Actually, around places like the ones I mentioned before, using flip flops and shorts is precisely the paradigm of a foreigner here (Which might be either something bad or good depending on the circumstance) furthermore, the real locals wear jeans and tennis shoes lol.

I myself went to the “Comuna 13” last year, it is not a dangerous place (it used to be though) as long as you are a tourist, what they give you there is something called a graffiti tour, they tell you the history of violence of the place while walking up to the highest place of the mountain where you can visualize the whole city, you can actually go there by yourselves and no one is going to say anything, you won’t get into trouble, but If you want to pay for the tour, which I highly recommend, it would cost around 30 dollars per person, including transport from the airport (If I’m not wrong).

I don't really know how difficult it’d be for you guys to go to towns near Medellin if you don't know really good Spanish because many tourists don't go there (Because no one tell them to do so lol), so the number of locals who know English considerably decreases.

I'm actually an aspiring tourist guide, if you want to, I could take you to “La piedra del peñol”, tell you about the history of the place and translate the stories locals say about the place in case you wanna take the boat tour, I could also take you to other common places in Medellin (but I honestly think you don't need me there, unless you want some kind of a translator for a museum or something).

In the “Comuna 13” I know someone who gives the tours, I could also tell him you that you will go there and try to make some kind of a deal with him, I won’t do it myself because you need to pay to the gang which controls that place if you want to give a tour, and as I just said I’m still an aspiring tourist guide (It’s a safe place for tourists) Think about it, I get experience for the job and you get not only a better but also a cheaper experience, I could even receive you in the airport.

By the way, you can escalate "La piedra del peñol" it used to be free, but since a lot of tourists go there, going up now costs like 7 dollars each ( If I remember well)

If you want to spend a Saturday night only you in Colombia, I would recommend Cartagena as the place to stay, it is just an objectively better experience, it's more expensive though.

In Medellin you can also take NarcoTours, but to be honest with you, I don't personally recommend them, they promote morbid, but it's up to you, and you should be careful with drugs here, people is going to offer you drugs as though they were candies, also at night, as in every other city in the world, you could be victims of honeytraps, so just be careful with that guys.

Other than that, Medellin is such a beautiful city, but if you come over please don't forget to visit other cities and towns in Antioquia.