Often times, the decision of where to divert to involves more people than the two people up front. At least in my experience, the dispatcher talks to the original destination station, and planning to decide where the best place would be to send the airplane, crew and pax.

After that, they come to the crew to see if we have the gas and weather needed to reach that airport legally.

EX/ Enroute to Gunnison, shot approach once, no joy. Told dispatch to begin working on PLAN B while we shot another approach. No joy, began holding. Got SELCAL'ed shortly there after with new destination of Montrose, even though the original alternate was Denver. Apparently getting busses to Gunnison for the pax was easier from there, and thats where we were supposed to overnight.

Got there, went to the hotel, new crew showed up an hour later and started their day on time.

This type of intelligent decision making doesn't always happen. This was just one good example.