In general, a 3.46 unweighted GPA or around 3.8 weighted is within the range of what is typically required for admission to Boston College and New York University. However, the average GPA for admitted students at BC is around 3.8, and the average GPA for admitted students at NYU is around 3.7.
In addition to your GPA, your SAT score of 1970 is also within the range of what is typically required for admission to BC and NYU. The average SAT score for admitted students at BC is around 1480, and the average SAT score for admitted students at NYU is around 1500.
However, your chances of admission will also depend on your extracurricular activities, letters of recommendation, and personal statement. If you have strong extracurricular activities, letters of recommendation, and a personal statement, you may be able to overcome a slightly lower GPA and SAT score.
Ultimately, the best way to determine your chances of admission to BC and NYU is to submit your application and see what happens.