By a series of not-so-fortunate things and decisions, I now have a 21-hour layover in Los Angeles before my flight tomorrow to Austin; any suggestions? It’s 6:20 PM here California time.
I booked a cheap hostel near the airport. Now thinking of things to do.
Go to whichever Tommy’s is nearest and pig out on chili burgers and chili dogs. This is especially good if you went out and got massively drunk first but even without the hangover Tommy’s is the shit. Also the shits if you’re not used to them but live dangerously, I always say!
If your budget allows an Uber ride, Venice Beach is not too far away.
21 hours? Just in time to line up for security for the next flight. 
Sleep.