Speaking of Greece... It's difficult to look at the current debt crisis in Greece without looking at the 2004 Olympics in Athens. The Athens games went wildly beyond their projected budget (the Guardian says they were at least €2.4 billion over), a tab that still haunts the tiny country's economy. Greeks had emotional reasons for bringing the games to Athens--Greece is the birthplace of the Olympics, after all--but they don't have the stomachs for the austerity measures that now have to be force-fed by the government.
Lesson number 1: Regardless of their size, games MUST have the financial backing.
Which leads to Salt Lake City. The projected budget was nearly that of the much larger summer games in Sydney 2000, but Salt Lake had the backing of the world's largest economy. And the Salt Lake games paid off: "[Salt Lake City Chamber of Commerce Spokesman Marty] Carpenter said the Salt Lake Chamber credits the Olympics witw(sic) $4.8 billion in sales, 35,000 job years of employment, $1.5 billion in earnings for Utah workers and, as well as $250 million in venture capital, from 1996 to 2002." The 2002 games themselves cost $2.1 billion, but over a 5 year period from 1998 to 2003, they generated a net revenue of $76 million for the state and the country. The lesson from Salt Lake: big games must have big backing.
The 2010 games in Vancouver will likely have the same effect, though it's too soon to tell for sure. A few effects have been measured: "Two other reports released by the provincial and federal governments earlier on Friday said the 2010 Olympics created more than 45,000 jobs and generated as much as $2.5 billion in real gross domestic product." What's more significant is this: VANOC reports that the games came in on budget and on time, something "remarkable" given the global economic climate of the years leading up to Vancouver 2010. Likewise, Vancouver had the backing of a moderately sized and what is generally viewed as a responsible economy. The lesson from Vancouver: well-managed games leave a positive legacy and can make money even in a poor economic environment.
Let this be the "no-duh" outcome of the story, for 2020 bids and future bids: Olympic bid cities must first show financial backing.