Now on to debt: Greece owes some money. It's a nation. California owes some money; it's a state. And, the US owes money. If California were to serve in full its debt, and arrange that it no longer had to incur debt to pay its employees, or raise greater taxes to do so, I would say it became solvent--however, if the day after the United States Treasury defaulted on its multi-trillion dollar debt, California would find itself in trouble all the same. So, really, California also owes a share of the US government debt.
Is the similarity enough for California to emulate Greece should the latter emerge triumphant from this shitstorm? I don't know. But it's enough for a metaphor about the current problem.
I like your point on US debt, but the US is in a unique position in that it can print money if needed. Because the odds of a default are so infinitesimally small, I don't think it warrants any discussion when considering the fate of CA's financial issues.
Greece is in trouble because it entered the EU, lost control of it's currency, and as a consequence, cannot attempt to use inflation to minimize their debt. To make matters worse, their economy is a train wreck (professional guilds, rampant tax dodging, heavy reliance on government programs) making growth in the face of austerity nearly impossible. CA has neither of these problems (A dynamic, innovative economy and a strong federal government to rely on for assistance (as compared to the relatively weak-willed EU)).
The size of the ballpark depends on the ball game. As far as heights, if yours were half of mine we would not be playing in the same league, let alone in the same ballpark at the same time. But wealth's utility falls off very quickly (cf. log-utility), and to this day Greece is a member of the OECD.
Greek is in trouble. There's no denying that. California, not so much. Still in some. But the worst may have passed already, because it's better grounded: on sovereign US soil, that strong federal government you mentioned. It's a state in a good federation, whereas Greece is in a bad (weak-willed = opt-in) federation.