I would turn the entire front gardens into an organic vegetable garden to be run by various shelters for homeless peoples foods, and for myself, elected officials and the staff.*
I would remove all the art from the white house, and move it all into a public museum called "White House" and fill the rooms with bookshelves.
I would put solar panels all over the white house roof, to the point where it's creating electricity to feed into the poverty stricken neighbourhoods for free electricity.**
I would upgrade all the security around the white house so that the entire thing is run on OpenBSD, with 40Sysadmins/shift maintaining the network security and T3 connection.
I would replace all the chairs with la-z-boy recliners, and the Presidential Chair in the Oval Office would be the ultimate massage chair, with enough room underneath the desk for BJs.
* This way the poorest people in the city, are eating with the most powerful are eating.
** This way the most powerful people in the city are providing free electricity for the poorest.