@eblicharski, unless you purchase a roaming add-on then you won't be able to use any data on your phone. However you could download the map of where you're going directly from google maps and you can use the downloaded map without data (just download it now). However, I don't think you'd be able to use the "direction" service without data.
In my opinion just purchase the data roaming add-on and save yourself from all the headache. Starts at only $10 and if you only need it for the maps then that should be plenty, unless you're gone for a long time. I went to New Orleans in the summer, purchased the $10 250MB was there for 5 days and that was plenty, was a life saver. Last thing you want to do is get stuck with no service when you need it. Not always fun running around looking for a wifi hotspot.
