Can you explain what you want in a university?
I have visited Washington University in St Louis. I had a great tour of the campus and of St Louis, and got to participate in a seminar. The students were smart and engaged and asked great questions. The students and professors that I met with were excellent. I definitely would not call it an “Ivy safety” school.
I think that you need to understand that which university you attend is not the most important thing. What you do when you are there is much more important. You will have a very wide range of opportunities at WUSTL or at any other “top 200” university. You will find other very strong students. You will find strong professors. You will have opportunities to participate in internships or in research. You do not need to attend an Ivy League university to find any of this.
You will also find other students there who are way smarter than you expect. This will not be the same as high school.
In an article in their alumni magazine a few years back Stanford said that 80% of applicants were academically fully qualified to attend. Yes, you are probably in this group. However, a year ago they only accepted 4.3% of applicants. I doubt this year was much different, and yes it was probably slightly worse.
I do not see much harm in taking a gap year so long as you have something productive to do when you take the gap year. I would not expect your admissions results to be much different. You might however gain a different perspective on life.