Hi, I just want to list some things for you to consider:
-	If you buy it from Bulgaria, but you want to use it when you go home – make sure it supports the GSM frequencies used in USA. Actually, because you like to travel a lot, maybe it is good idea to get a quad band phone. 
-	Latest models are announced here with great delays. You may want to check the alternative shops like Germanos, Jeff and online places like mobilebulgaria who may be able to offer you newer model phones that are still not available in our carriers’ shops.   
-	If you buy it from USA, you probably will have to pay the full unsubsidized price, because you do not need 2 year contract in US, but even then the price may be cheaper than what you will have to pay in Bulgaria for the same phone, if it is offered here at all. Again – you will have to check the supported frequencies. 
-	Make sure that you have some data plan. I guess you will want to use it for email, twitter, etc. I think 250-500 MB/month are enough if you do not play too much online audio/video content. 
-	Be prepared to charge it every night :)
-	Do not expect to be running Skype flawlessly and have it always on. It will shorten even further your battery life if you have it always on.
-	If you get an Android phone, using Google Voice you can make free calls to US, so you will be able to contact your family not only from your computer via Skype. But the call quality may not be very good. Sometimes these features that sound great on paper are not that good in real life. See this link for more info: http://www.pcmag.com/article2/0,2817,2383262,00.asp