This is one is actually very difficult. But I think for one day I would want to switch places with either President Obama or Richard Branson.
I pick Obama because I would like to have his job just for one day to try and reform some of the US policy that I find contrary to the interests and the values that the country hold. The country professes so many things and then has policies that work contrary to those polices.
I picked Branson because of the resources he has at his disposable and I would find it interesting to try some of his toys.