You obviously know USC well and I can’t speak to Northeastern, but A few things to consider:
-WashU has a very well respected entrepreneurship program at the MBA level. A lot of that will translate down to the undergrad b-school level. How much I don’t know. You need to investigate that.
-I’m not sure why you think CMC is way too small. About 1500-1600 first year full time students enroll every year. At WashU it’s around 1800-1900. USC is 3400-3500. I don’t see a big difference between WashU and CMC. If CMC is way too small, WashU won’t feel appreciably bigger. When you actually drill down into classes in your major, there’s a good chance you won’t be particularly anonymous in any of your core classes. By my jr/sr years at WashU, I probably knew 60-80% of the students in my major-centric classes. Even at USC, you’re going to know most of the people in your Econ program by the time you hit your 4th upper level class. There aren’t that many Econ undergrad diplomas minted by any of these schools on an annual basis.
-WashU has a lot of flexibility between the undergrad colleges as well. If you want to mix Econ with entrepreneurship via Olin and film, you should be able to do that. I don’t know what the requirements are for film. The only limitation is a hypothetical switch to engineering/applied math. Engineering/applied math is highly sequential, so you’d need to make sure that you are maintaining sufficient progress in those areas to keep that possibility open. That would apply at any of your schools though. The good news is that there should be decent overlap between Econ and applied math.
-I would not sweat the recruiting that much when it comes to schools of USC/WashU/CMC caliber. Is it easier to get your foot in the door on the West Coast with a USC degree? Yes. Will it give you an advantage vs the other two if you decide to go to grad school in CA? No.
You’re going to come out of undergrad with a 40 year career in front of you. USC might help you land your first gig more easily. But in the long run, you’re going to progress based upon your abilities. 5-10 years out you’ll be where you are based upon what you did post college. A classmate and friend of mine left STL with an English/Psych major and drove to LA with the idea she wanted to write for TV. She’s an executive producer for a show with over a dozen Emmy nominations. Any of those schools are good for what you’re trying to do. What you do with the opportunities that level of education provides boils down to diligence, resilience and hustle.
-I wouldn’t view going to school in STL as a negative. Plenty to do on campus, in the Loop, Central West End, Forest Park, etc. Good undergrad restaurant scene and people attending are from everywhere. People are friendly, but student body is decidedly not “Midwest”. It’s actually a very good city to attend college. It’s pretty similar to Pittsburgh. STL has marginally better weather but PGH is a bit more urban/dense despite being a bit smaller.
-I’m terms of all of the schools, you will find diversity of interests/backgrounds. USC is definitely the most Greek/athletics influenced, but you will find “your people” by interests, socioeconomics, etc at any of those schools. It might be easier to find your people at WashU/CMC, but they exist in large numbers at a place like USC too.