Jim my wife and I were recently in the US for The Masters.I was able to use my work mobile on the Vodaphone global roaming but we purchased a T Mobile Tourist Pre Paid card for my wife and it was great. Coverage in and around LA and between Atlanta and Augusta was superb and was generally shared between the T Mobile and ATT networks.It gets great write ups on the travel pages such as Trip Adviser and we found it worked exactly as promised.It is limited from memory to 3 weeks so if you will be away longer you may need to look at alternatives.