FWIW, I know there are something shy of a billion brands of SIM cards out there that will fit the iPhone 4s (my wife and I each have one). I'm still trying to figure out how much "data" I'll need for things like sign translations - using one of those apps to take a picture of a menu and have it translated to English sounds fantastic but I haven't seen any numbers for how much data goes back and forth.

Now that I'm back from California, the *real* research starts for this trip...