Default is a credit death sentence. Please understand, sovereign countries can NOT declare bankruptcy and refuse to pay. The debt has to be paid unless you can get the creditors to be magnanimous and forgive a portion of it. Otherwise, until you pay it back you will be bared from all credit. Greece has already gotten their "haircut". They will have to pay back every dime or they will never borrow money again unless they can get the ECB or IMF to agree to another haircut which isn't going to happen.
You should see what default did to Argentina. It destroyed the country and it continues to wreck havoc on the economy a decade later. Small countries like Greece have to borrow money because they generally import most of their products and obtain most of their foreign currency through tourism. If you shut of debt they will be unable to purchase anything on the foreign market without first obtaining equivalent amounts of foreign currency first. Even with a very strong tourism industry and positive cash flows from the tourism this will be very painful for every single Greek.
Sovereign countries cannot just decide not to pay debts. There is not bankruptcy. Greece has one choice, here, pay the money or default on payment and pay the money later after suffering for several decades. There aren't other options in this world.