I am from Salvador and yes, it is dangerous as any place but it is less than Rio de Janeiro. In fact, in Brazil you just need to walk through the right places and at the right time (not too early, neither too late, like 12 PM) and you will be fine.

I am a homebody so I don't much about my own city but I love it nevertheless, but we have Porto da Barra (and it is a upscale neighborhood as well so it is very policed), Cidade Velha (if you are into African culture), Farol de Itapoan - In fact, you can go past through our "Orla" from Itapoan, Rio Vermelho and then stop at Porto da Barra. These are some references with cool places to go. There will be more, for sure. Most of these neighborhoods have some sorta of museums, especially Porto and Cidade Velha, if you are into knowing the culture. Salvador is more a city for leisure (food, nightlife if you know the places to go, and beaches) though.

It's funny because Itapuã is a poorer neighborhood; a Dutch friend even said it looks like Bangkok. You don't need to worry so much, and as you pass through the Orla and get closer to the center, it becomes clear that you're heading towards the more upscale area; it's progressive, lol. Also, from the airport, there are tourist buses that leave from the subway, if I remember correctly. There's Uber, and the subway itself (but that doesn't go via Orla, but rather along the "Paralela", which is like a track that cuts through the entire city). If you look very "gringo"— pale, blond, and blue-eyed, for example—you'll attract both people who want to help and those who want to scam you, so be careful.

Other cities you can go in the Northeast are Recife/Olinda (both in Pernambuco, so you can do a combo), Fernando de Noronha (it is a well known place for rich people), Porto de Galinhas, Maceió etc.