Most decent charities deliver far more per unit donated than the US government could ever wish to achieve. If you're interested in pure charity, you're not going to get much bang for your buck at the federal level.
as greenspun says: "The federal government funds roads and airports that we all enjoy using. The feds pay for health care for the poor and the old. Our tax dollars pay for intrepid military personnel who go out and kill angry foreigners (in most cases) before they can arrive on U.S. soil and kill Americans here at home. For a non-profit organization of its size, the federal government is surprisingly efficient. Most federal employees work in big box-like office buildings, not in $300 million monuments to an architect's ego. George W. Bush gets paid only $400,000 per year, less than half of what a lot of university presidents earn."[1]
I personally have a somewhat less charitable view of effects of military action, at least the military action during my lifetime, but I do think that most of the personnel involved do believe that they are doing the right thing, and those other things, roads and healthcare and stuff; those are pretty great to have.
Now, I'm too lazy to dig up non-greenspun references, but it seems that many non-profits serve up rather nice salaries, for rather inefficient work[2]
[1]http://web.archive.org/web/20090217002255/http://philip.gree...
[2]http://blogs.law.harvard.edu/philg/2010/07/27/where-your-cha...
Who pays what in taxes is really a diversion.
The "who" is actually pretty important.
Tax the working man more, and you'll discourage working. Tax the rich, and he might move to another country.
There are many ways to raise money for the state, and none is really "fair". There will always somebody who'll be screwed in some way.
Most major donors contribute to things they can put their name on like buildings (see Stanford campus). It's difficult for even most charities to cover operating costs (i.e. labor) with only donations. Most have to apply for grants or do lots of funny numbers to keep their administration costs (i.e. labor) low.
The American Red Cross, a large, established, and reputable charity, has about 9% general and administrative costs: http://en.wikipedia.org/wiki/American_Red_Cross
Medicare, a large, inefficient government fiasco (note: irony) has 3% overhead: http://healthcarereform.procon.org/view.resource.php?resourc...
Many charities do far worse than the ARC.