Let me preface my response with this: My dad was in the Navy, one Grandpa in the Army, the other in the Air Force (POW in WWII), and my uncle was a Colonel in the Rangers. I have friends actively serving and deployed.
I thank them for signing up and being ready to defend my country and lay their life down to defend our freedoms and country. However, I don't understand how people keep signing up for the military at this point, considering we're in 2 wars that have long since run their course, and I don't think Libya is ending any time soon, though our minimal engagement now makes that less of a concern. Frankly, at this point our soldiers aren't so much defending our freedoms and rights as being the world police in place of the UN. I think the amount of people still joining has a lot to do with the nationalism a lot of our country feels (America is the best, etc), and families like mine where it is almost expected that you join. During times of real threat (WWII was a great example), I wouldn't hesitate to join, but as of right now, it would take conscription to get me to join. When people come back from a tour of duty, there is certainly a bunch of prestige given to them, so that may draw some people in. And I'm sure there is a certain draw for people to join the most advanced military in the world.
On the political side though, a decent portion of the country would like to see military spending cut dramatically (not sure if that is +/- half). In 2008, our spending on the military was over $700 billion (revenue was hovering around $2 trillion..so about 1/3 of our money went towards just the military). Europe (the whole continent, not any single country) spent about $240 billion, and everyone else spent less than that. We certainly need a defensive military, but at this point we can't help but be the world's police, because otherwise we'd never get to show off our cool weapons. But that's a different debate, really.