Choosing Resident Alien for the whole year

[stuart1]

My wife and I moved to the USA for my work in June 2013 and by the end of the year we were both resident aliens. We had no international income in 2013.

1. Is there any disadvantage of us choosing to be resident aliens for the whole year?
2. What declaration should we make to be treated as resident aliens for the whole year?

Thanks in advance