Most of the regional differences I notice involve vocabulary, gifting/hosting, the pace and of course climate.
Calling all soda Coke was the strangest one for me since Coke doesn't even begin to cover all the flavors available. It's not a brand with one meaning like Q-tips.
I say...
Sneakers, not tennis shoes.
Hero or sandwich, not sub or hoagie.
Soda, not pop or coke.
Every wedding I have been to served alcohol and a meal. I have only been to one wedding had a cash bar in CA (I live in NYC). I give a gift at wedding showers and a check at weddings.
NYC is very crowded and people move fast and with purpose. Some people are aggressive, some are rude but most are just trying to get to where they want to go with as much ease as possible. I know I get into a zone sometimes and I just want to get to where I need to go that I could walk by a long time friend because I am just focused on my path. Think Disney crowds almost all the time...people slowing down, blocking doors & steps, randomly stopping. On vacation it's annoying but it's a way of life here and it takes a toll. It's nice when I visit my mother in Florida and people make eye contact and smile.
Climate is what it is. People in CA can laugh about NYers being a little freaked about an earthquake but we can handle a several inches of snow without much of hiccough when a half an inch of snow in the south shuts down the town.
The differences make the world go around!