LEM,
There's too many variables in the equation for a specific answer. For one, there's a helluva difference between diverting to an airport 50 miles away to 'sit out' an hour long period of lousy weather at the destination, and a diversion to an alternate 600 to 700 miles away.
Another big factor is local knowledge, at one of our regular airports, when the fog rolls in the airport remains closed tight for at least 3 hours. Much better to divert to the 120 mile away alternate than going around in circles at great cost to the company when you know there isn't a chance of getting in for at least 3 hours. More dynamic situations like passage of fronts etc. you know are going to clear in an hour or so, and it's better to hold whilst it all passes in the knowledge that you have a very high probability of a successful approach in an hour or so.
Each Airport / Traffic / Weather situation is different, too many variables to arrive at one common solution for all cases.
Mutt, you wouldn't happen to work for an airline from a certain oil-rich country would you?
Regards,
Old Smokey