Hmm…I grin at number 17. It’s purdy… and the “largest living thing on earth” blurb is amusing. It should say HOLY CRAP! across the top, right where it says “Califonia” 
I dunno about the unifying the state thing. I was born in Southern Cal and now live in Northern Cal. Hmm. I was originally fixated on 16 but now i think it looks kinda busy.
cocks head to the side at Coin 8 What is that? DNA? Hmm. Wierd.
Voted for number two.
Thanks for the link to this site, Dooku. 
I’m really not a fan of #11. It looks too much like a Boy Scouts merit badge. I can’t imagine it on a hard surface like a coin.
I’d have to go with either 2 or 3. 2 because it has two major California landmarks, along with palm trees, which I think captures the beach atmosphere of the state. 3 because the areas outside the cities like Yosemite don’t get nearly as much as attention as the big California cities, so it’d be nice if the coin showed a different view of the state sans all the glammor and glitter. Plus, we can brag that we have 100 foot tall bears roaming our forests.