I echo some of the sentiments on Tokyo.
Amazing city, best in the world, as someone else living in Japan--remain as a Tokyoite, especially if you've broken out of English teaching into a real job and have established yourself with a nice condo and a nice ride.
Tokyo is pretty much amazing after having spent a lot of time there if you like crowds; personally for me, the denser the better--I get a boner off of 5,000+ people per square kilometer density, but most others probably would hate that; but by now you know if this works for you or not which it does.
Another thing to consider is indeed the work hours; as a foreigner are you getting to gaijin smash your way out of that or have they assimilated you to the point you sometimes work 60-70 hour weeks and weekends as well? Keep in mind the idea of glass ceilings for foreigners in Japan and how far you can truly advance and whether or not it will meet your wants in 10-20 years. I know in my industry I could never have as much in Japan as I could back home.
But, Tokyo is awesome--amazing night life, biggest city in the world, SMOKING hot women/fashion absolutely everywhere that girls back home couldn't pull off no matter how hard they tried, amazing restaurants (I don't even like Japanese food but they have mastered restaurant ambiance), izakaya, very safe, best public transportation in the world, kind people, etc. etc., the list goes on.
I know nothing of LA but my impression is that sun gets old and boring real quick (as someone who's from Minneapolis originally), and you get a mix of real California Abercrombie surfer douchebags and dreamers (idiots) who don't have a brain in their head but think they will be the next big thing and move out there without a single iota of thought.
Chicago--what a let down, that's all I have to say about that place.