I feel your pain. I am a dual citizen and have a large student loan debt as well, and the degree is now useless. As tempting as it is to move away and never have to pay it back, I personally dont think its a good idea. If you ever, ever, ever decide to visit the US again, even years from now, you will have a huge legal hassle, and are you sure you want to renounce US citizenship? I am American, and I have my share of frustrations with this country, but you don’t know what is going to happen in the next 10, 20, 35 years. Maybe you will want to come back, maybe your children will want to come back? Don’t burn any bridges, I say, IMHO. I don’t know if they would come after you in Spain, but given how tight the world economy is becoming, I wouldn’t say its impossible.
BTW, I put my fed loans on the Income Contingent Plan, right now my payments are $0, in 16 more years, unless I start making a ton of money, they will be forgiven. Google the federal loan forgiveness program, as long as the Repubs dont over turn it, it might help you out.
Best of luck,
Laura