Thanks all!! I really appreciate your insights and thoughts!! Based on your responses:

1) It seems like 6A or 6F are the narrowest seats.
2) If I was planning on booking 3 seats for my family in row 6, for example 6A, 6B and 6C, there are only two seats in front of row 6, so one of my three family members wouldn't have a seat in front of them to stow their carry on.