this is certainly a complicated situation.

uhh

  it’s really not a very large problem

Ok.

  So you need to choose destinations for a few thousand planes? 

No. You need to figure out which planes are where, which of those planes are legal to fly out of which airports, which planes can be made legal to fly with low effort, and which planes need to go in for service (potentially requiring a non-revenue flight).

Ostensibly Southwest operates a fleet of Boeing 737s with two subfleets (ETOPS and non). The ETOPS planes can be used anywhere but the others cannot be used to Hawaii. Some of the ETOPS routes require the range of the MAX and some do not. Some of the airports Southwest flies into can only handle the smallest planes. It's entirely possible that everything stuck in Oakland is too big to fly into Burbank for instance. Or its entirely possible that all of the ETOPS fleet is stuck in Hawaii (so all of the routes too Hawaii are no-gos).

Then you've got to figure out what's broken on each plane. Depending on what's inoperative a plane may not be able to fly into a specific airport if the weather is anything but perfect. If enough stuff is broken the plane may be stuck away from a maintenance base and illegal to fly in revenue service. There goes a plane and a flight crew. These are laws, not optimizations.

And finally you need to figure out where all the diverted flights went. No idea what's normal but Southwest had to divert two flights today (one due to mechanical issues and one due to an unruly passenger). So there's at least one plane that's out of position and unable to fly until it's been repaired.

  Need captains familiar with the airports? 

No. In fact I'm pretty sure that unlike RyanAir and EasyJet, Southwest doesn't fly into any airports that categorically require specific familiarity and training beyond the ETOPS certs required for the Hawaii routes. You do need to figure out who's legal to fly in revenue service and who might be legal to fly on a ferry permit though. Southwest was pretty late to the autopilot game but at other airlines some captains are qualified to land in worse weather than others. So even if you have a flight crew ready to go they may be unable to complete your desired route today – and that's been a problem. The Southwest scheduling software assumes that every pilot completes their assigned flights successfully. Whoops.

Then you've gotta do the same with the cabin crew. And then you've gotta make sure none of this runs afoul of the various CBAs.

And you haven't even addressed the issue of out of position luggage. It's not just that luggage is piling up at airports, but Southwest's actually flown some of the luggage without the passengers.

When that's all said and done you're going to need to handle everything that goes tits up as service resumes. As I pointed out earlier, Southwest had at least two diversions today. So now you have two more out of position planes, crews, and more out of position luggage and passengers.

It's a massively complex, dynamic problem. If a couple million bucks would solve things, Southwest would've spent it already. List price on a single 737 is around $40 million. Even if Southwest got half off you're still talking tens of millions of dollars per plane.

  People who manage electric grids have protocols for “black starts”. These protocols are
  messy and complicated, but they are developed in advance, and they work. Airlines should
  have the equivalent capability.

Most airlines do but, based on the anecdotes from Southwest crew, Southwest does not. Again it's not really that Southwest flies point-to-point, and it's not just a software issue at this point. Procedures that worked when Southwest was a scrappy little airline simply don't scale and Southwest management is ill-equipped to handle this. It's all compounded by the employee contempt that Kelly's managed to foment.