Congrats on these opportunities! I think the visits will clarify things for you.
My daughter was an OOS student at UNC, and initially the social piece was difficult due to two factors: there were many instate students who seemed to already have friend groups, and she had some personal issues (thankfully she is fine now). Being an OOS student at a state school is good for some, but not for others. Thankfully it worked out and my D was very happy. She had friends from all over the country.
Greek life is not big, but it’s there if you want it. My daughter had no interest, and her social life revolved around other things.
The journalism school at UNC is outstanding, and she had a close friend who was in it and was (still is) quite successful in terms of internships, jobs, etc. I don’t know how difficult an acceptance it is. Being a direct admit at Northwestern is a huge, huge benefit
It sounds like Northwestern is your best choice (congrats) and once you finish your visits you may feel confident in your decision.