Afganistan: Was the juice worth the squeeze?

With almost 35 years of variable presence in Afghanistan, what have we gained from this desolate country?

Iraq: What did we gain?

We invaded Iraq in 2001, after the nation invaded its southern neighbor Kuwait.  We spent 100 days in Iraq, vanquished their Army down to nothing, and then left.  So, in 2003 we did it again, under the guise that the country was developing Weapons of Mass Destruction (WMD's), and then left in 2010.  My question is, what did we gain by invading this country? As a nation, did we add something to our GDP? Did our foreign policy get stronger?  What was the positive side to this action?