Have not been to Miami or Miami Beach in some years but they re beautiful, interesting, fun with lots to do and great nightlife. As some posted, Miami is one city and Miami Beach another.
But I m going to caution you.
You say that you are from Madrid so you know about thieves and pickpockets. And Miami has the same types of people.
You do not say if you are traveling alone or with another but do not leave any thing on your beach towel unattended or it is going to be gone. Do not trust ny stranger who tells you they will watch it for you.
In the clubs, do not accept. drinks from a stranger because it could be drugged. If you are in a club alone and need to go to the bathroom, take your drink with you.
Be cautious about who you get involved with because you could wake up somewhere thoroughly naked with everything gone.
I have heard of all of the above things happening. It makes the news.
In America, you need to be careful about personal safety. Most of us living in The United States are familiar with violence but a European visiting might not be.
Watch youtube videos and read up on violence and personal safety. Talk to your consulate before coming. Talk to friends and relatives who have traveled to the United States.
Be aware.
Miami and Miami Beach are wonderful but I want you to have. a really good time so I am cautioning you.
I live in Texas and Miami area gets very very hot very early. It is also very humid. Maybe this will not bother you but it bothered me.
You might try booking.com for. hotels. And then you cn post the hotel and neighborhood on forum and see what feedback you get.
I thought that public transportation was pretty decent in Miami. There is a monorail which I think runs mainly downtown and I think that i remember trolleys but public transportation is not going to be anywhere as good as Madrid or other cities in Europe.
I am going to look at some of my pictures and if I find any things to recommend, I will begin another post.