In all honesty, when it comes to making state characters I think it all comes down to where you are from. Since you're from the West Coast you are probably going to rely more on stereotypes, things you've heard about and your own personal opinions of the East Coast. I definitely agree with Pennsylvania being well educated and a gentleman. Though in the end I see him more as a clumsy sweet shy dork. xD If asked what people from Pennsylvania are like people often either say, "the people are so nice there!" or "that place is full of assholes." I think we're more soft-spoken then some of our neighbors, like New Jersey and New York. If we have something to say you can be sure you're gonna hear about it though. We don't know how to keep our mouths shut most of the time I've noticed.
Meanwhile I picture New York as somewhat of a badass mofo with a penchant for partying and a womanizing attitude. He has an ego the size of Texas and enjoys tormenting/picking on his younger brother New Jersey, but naturally deep down he cares about him. They are brothers after all and no one can mess with his little bro, but him. He's generally friendly with Penn, except football and baseball season, but tends to make fun of him as well considering he thinks he's better then anyone else. He's more of a city boy, but he likes to escape upstate to the countryside every now and then. Despite this he still picks on the Southern states as well as Penn (my version of PA is more of a country boy then city boy, though he does love his cities as well.) He can fall under the category of 'jerk with a heart of gold.' He can be a cool dude when he wants to be.
Then my head-canon New Jersey is highly sarcastic and somewhat of a cynic. He puts off the tough guy impression and certainly he is tough. You have to be to survive in Jersey. Most of the time he despises his brother, but he does actually care about him. He likes to pretend he doesn't care about anyone when underneath it all he's a bit of a softy. He enjoys gardening (he is the garden state after all) and will kick your ass if you dare question his manliness. Gardening is manly damn it!
He sees Penn as somewhat of a rival and like to pick on him. Penn just usually ignores him. They have times where they can get along, but most of the time it's rare. This is actually basically my friend's NJ though. She's from Jersey. We started a state RP not to long ago due to boredom. This is probably part of the reason I Like NJxPA. *Shot.* Her Jersey likes my Penn.
I've noticed most people make California a whore and I think that's actually pretty rude. 0.o My head-canon Cali is a rather clever, somewhat badass woman. Maybe a bit on the spoiled side, she knows what she wants and is very picky. Perhaps a bit flirty and seductive, I don't really see her actually sleeping with every guy who wants some like some people describe though. However, I've never been to California and live pretty far away so I honestly don't know to much about this state yet except for your basic history.
So those are my versions of the states in least. Oh dear...this was very long. Me and my rambling again. I'm sorry.