Personally, I believe that immediate "Grexit" is preferable to yet another round of destructive austerity. Maybe there are enough members of the Greek parliament to say "no," as the Greek people said "no" last week. Okay, I understand that a substantial majority of Greeks want to stay in the Eurozone, but it won't do them any good if they have no euros to spend.
The euro was a bad idea from the beginning, as the British recognized when they opted to stay with the pound. Not only Greece, but Spain, Portugal, and Italy would enjoy a great deal more economic autonomy if they had their own currencies. If Europe ever is politically unified, that will be the time for a unified currency. All the euro has accomplished is to put the bankers in charge.
In the meanwhile, it's time for Greece to cut its losses and default. The future is grim for Greece no matter what it does, but real recovery will come sooner if Greece has its own currency.