Swedish or English… thats the questions :)

I am thinking about writing in English during my time in USA, mainly because I hope it will improve my English skills but also so the friends I hopefully will meet abroad can understand what I am writing. What do you guys think? How much will it improve my English? Is it worth the extra effort? I created a Poll on the right sidebar so you guys can vote in which language I should write in, the poll will end on the 10 of August.