While in UK, you can fly to various countries within a few hours, the same is not the case when you are in America. Just within the country itself, you can be in the air for at least around 6 hours and you will still be within the country itself. For example, the flying time from Seattle to Miami is around 6‐7 hours and you will still be in the same country, similarly the fight from New York to Hawaii can be anywhere from 9 hours to 11 hours depending on the route that you take.
With so many variations of air travelling time, the one thing that can be a major concern would be the roaming charges that would be applicable if you use a mobile while you are in your own country. For those who are using their iPhone in their own country and have the benefit of any amount of texts and calls at affordable rates, the data can be one of the main pints that determine the kind of plan you would go for and how much you would have to pay.
However, if you look at the larger pictures, the amount that you would pay while you are overseas would be a lot more than what you would when you are on roaming within the country itself. There are a few packages that are available for data while you are on roaming however the data allowance that you would get would be a very small amount. If by chance the allowance of your data is exceeded you either have the choice to go ahead and use your phone only for calling purpose or go ahead and opt to pay a separate amount just for your data. It is purely up to you as to how you want to go about using the data of your mobile.