Congratulations on your acceptances!!
You really can't go wrong either way but I'll put in my 2 cents based on when I faced this decision a few years back:
To answer your question, I personally feel that it's more difficult to move East from UCLA than it is to move West from Yale. How did I reach that conclusion? At both schools, I spoke with Admissions, the Career Offices (and placement stats), alums, and current students looking to make that move. From what I heard and saw Yale had much more reach with West Coast firms in terms of firms coming to campus to recruit and actively seeking out students (and vice versa) for summer internships and full time placements. This holds across industries -- tech, consulting, finance, media and entertainment, healthcare, etc. I'll caveat based on small sample size, but the people I know from UCLA who did the East Coast search all ended up staying in California for internship and full-time roles. Some moved East later but from what I've seen that's more of a long-term plan.
At the end of the day, you should figure out at a high level what you want to do immediately post-MBA. Presumably you wrote something in your application...has that changed? Stayed the same? Which school will put you in the best position to reach that goal -- and give you the option to explore other options while you're at it?
If you're looking to stay West Coast -- and potentially are already West Coast based -- UCLA will be a hard choice to turn down.
If this is about $$, as
8088 said, reach out to Yale to see if they'll match. You don't know if you don't ask.
One last thing .... look into fit. Attend the admitted student weekends for both schools if you can. Culturally they are pretty different schools IMO. I have been around both schools a lot over the years and they are not equal substitutes. See which school and their students is a place/are people you want to be around for the next 2 years -- and be apart of their network for a lifetime. I think it would be remiss to choose a school only based on career placement stats and not actually enjoy your time at the school itself.