If u look at the OECD forecast it is puzzling. Euro are has better fiscal position as well current account surplus. It has almost same inflation as US and favorable short term interest rate. So it has better forecast for the variables which drives GDP and Employment but it has worse forecast of GDP and Employment as compared to US. It is clear that Euro area as such have no problem in terms of macro-economic variables (even its 110% debt GDP ratio is well below the Japan 170%), if that would have been then US must also suffer. So it is clear that problem lies elsewhere. First thing is the reserve currency status of USD. Euro is reserve currency but not has a status similar to USD and more over there is no political unification i.e.Germany or any country which are in good shape would not support printing of Euro and giving it to problematic country which is not in the case of USD and it can be printed by any amount and it does not matter that problem is in Alaska or in New York.So this present crisis has proved one thing said long ago by Mundell that if regions suffers from idiosyncratic shocks they could not be an optimum currency area especially without political unification.
Second reason for the above crisis may be the bad policies in Euro area where Greece has been integrated without satisfying the condition and German policy of lending for its own export particularly Military goods. There is no doubt that Germany has been benefited on the expense of other countries.Since the other countries exchange rates are overvalued in terms of German currency.( I am talking about relative exchange rate taking price in to different market as variable). So the devaluation of Euro would not help problematic PIIGS. They need relative price fall and the options are deflation and break away from Euro. They have started the first and lets hope that it works without creating enough problem.
USD; United States dollar