when I grew up in philly everybody had sweet sixteen's. My mother and her sister had sugar cube corsages. She thought I was going to do the same thing for my dd, but here in south jersey nobody does it. We had a slightly bigger birthday party, and my mother got my dd a sugar cube corsage.
When my family was bigger we had a hall for first b'day, christenings, 16th b'day, showers, etc...
I think the sweet sixteens and other big parties might also be ethnic. We are an Irish Catholic family. And when you get closer to NYC you get a higher concentration of ethnic groups who tend to do the bigger family things. There was just a program on the local talk radio station where people are predominantly from N. Jersey. Even though people from all over the state were calling in it was the N. Jersey folks who had NY roots who were doing the parties.
My sons turn 16 in a few weeks. I was trying to think of something special to do for them.