If I end up playing, I'm thinking of snagging some territory in Mexico, or maybe in Panama. Those are both fairly out of the way, yet could get involved in different ways. (I.E. a Mexico concerned with restoring the old country may try invading California/Texas, and Panama could try and become a proper merchant state of the new era.)
EDIT: Alternatively, I'm kind of relishing the idea of creating a Pueblo state, too... EDIT 2: Or someone that wants to reform the Comancheria, putting them in direct conflict with Texas. Or some Quebec nationalists that finally get to see their crazy dream realized. ...Hmmm.