Although we are getting away from the original point of the thread, just wanted to put in a strategy for people who find themelves culturally isolated.
I was once culturally isolated on three sides, and my fourth side being ocean. Two of the cities were costal and one was two tiles off the coast. So I pretty much looked liked current day Portugal, except with three civs surrounding me. I was playing on Pangea.
After a few possible plans, I though back to the novel Grendel (based on Beowulf) where Hrothgar never attacks his six closest neighbors. So I made great friends with my three borders and immediately got open borders. I then set up multiple attack forces within my northern border (Persia) and attacked their northen border of Arabia. Easily took most of Arabia. I then through there attacked Arabia's eastern border, taking a few cities (Aztec) and attacked Aztec's southern border (France) taking two cities. I now had a great empire in the middle of the pangea, and three cities (including my capitol) unconnected in the southeast. Now was the time to attack my neighbors. Since my borders were so vast, I was able to attack Persia on three fronts and my eastern border (I forget who) on two fronts.
Lesson: If you ever find you screwing yourself on settling and becoming culutrally isolated, make friends with your neighbors and attack civs who do not border you. This way you just ask your neighbors to close borders with the opponent, so you can attack them, but they can not get their forces to you for a counter-attack.