Around the World

i don't know about what to recommend, but you don't have to have a plan to go internationally when you buy an unlocked phone. if you search around ebay, you should be able to find an unlocked phone that you like for a decent price... and once you get to panama, you could get a prepaid sim card and put it in your phone.

and anyways, as of a few weeks ago, it's legal to take a phone to your carrier and get it unlocked for free.