Local here. Brickell is a great place to start. There are lots of open air shopping and restaurants within walking distance. The mayors, both city and county, have really endorsed new urbanism and Project Zero ideas. I moved back to Miami about 5 years ago. 10 years before that you were taking your life in your hands by walking out the door. But they are building out dedicated bike lanes, public transit, and actual sidewalks.
If highrises aren't your deal across the bay is Miami Beach. The apartments and bungalows are smaller and low slung, the city is infinitely walkable, and you are a few blocks from one of the best beaches in the world. It's still relatively affordable, but not for long.
The actual tech scene is miniscule and feels like I'm at a dentist convention happening weekly. A lot of our co-work, makerspace, and VCs host mixers and happy hours. This is more for new arrivals than anything. Old tech prefers to live out west and north. There is still a lot of radio and aviation tech that happens away from the startup scene. They don't attend the meetups.
Job wise it's not the best. If you come here with remote work contract you are golden. There is a lot of LatAm and Caribbean tech companies who tend to be penny-wise and pound foolish. Salaries are lower because why pay NYC/SV rates when you can get a fresh CompEng immigrant for cheap and who'll culturally be a better fit.
What we do have is a lot of regional sales and finance offices in the downtown core. This masks the fact that they are just the go between and don't have a lot of decision making/innovating going on. For example, Miami technically has the largest number of banks in the US outside of NYC. Microsoft, Google, Dell have a regional office here but no actual engineering goes on there.
At one point career wise I got trapped here and vowed never to return. But wanted to have my family be closer. I had a remote job with a European tech company until that didn't work and now I'm working for another tech company in a different field. A lot of companies are supposedly looking for senior engineers in a city where there barely any mid-level engineers. So the benefits to local talent seem to be wasted and creating some resentment.
The entire tech scene is just a pocket. It entirely fits in a few square miles; almost all of it east of I-95. Living here is going to be a culture shock for a lot of new arrivals. You'll wake up one morning and see Santeristas sacrificing a chicken and that sort of thing.