President Obama visited one of my Marines in Bethesda and personally pinned on his Purple Heart. He took quite a bit of time (for the President) talking and visiting with the family. My Marines mother cried on his shoulder (literally) for several minutes.
There were pictures taken by the White House staffers (I have a copy), but that was primarily for the family. He had massive eye injuries and was in and out of consiousness during the ceremony, so it serves as a great momento for him as well (since he couldn't see anything). You'll never see/ hear about this visit on the national news.
At least in these instances the President is 100% genuine and is providing an invaluable boost to the morale of the servicemember and their families. That goes for President Bush as well.
I'm all for a good cynical conspiracy theory, but I'm inclined to give our Commander in Chief (no matter who he is at the moment) the benefit of the doubt when it comes to personal visits with wounded or fallen troops.