When I travel overseas (generally Asia), I get the AT&T intl roaming data pack (I think it is 50 mb?) and will turn off all of the push notifications, locations (except for maps and camera) and will turn on roaming only when I want to use the map or check email, etc. The phone still works and I can send/receive texts. To surf the web, etc. I'll use the hotel wifi but will turn on data roaming if I need it, like to check the location of something on the map, etc. I'll also reset my data usage to zero when I get on the plane so I can keep track of data usage during my trip.

This method works for me but I'm never gone more than 2 weeks.