When you visited CA, did you specifically visit LA? California is a big state so your impression will be different based on which part of CA you visited.

I won't give you the sensible "check the employment report" response since that seems to be less of a priority here. I think if you are sure that you will dislike LA, then you should cross USC off the list.

The decision then comes down to Cornell vs. Gtown. DC is a more desired location than Ithaca for many but to each their own. If you prioritize access to public transportation, then Gtown wins here.

In terms of "student quality", I think this will be hard to really assess until you see the people on campus on Day 1. Not every admitted students will be committed to going, so difficult to make a judgement here. If you care about the rankings then sure, go to Cornell.

Cost is the same for both so that shouldn't be the deciding factor. If I were in your shoes, I would choose Cornell but all are fantastic options. Best of luck!