Surprised that no one has commented on this question so far, @RoderickJ614381 . Looking at your AARP profile here, you are more of an expert on banking and financial advice than I am, but I would think for the average senior who only has a mortgage and maybe car loan to worry about, the answer really depends on what kind of services are needed from a bank or credit union, wouldn't it?
Convenience of location and parking is a big factor for me. I don't like driving into the city and/or parking in a several story garage, or parallel on the street. Give me a good suburban parking lot! LOL The other big factor is no-fee accounts if maintaining a certain balance.
I appreciated having a big bank branch in my nearest big box store until they closed the branch recently. I liked having my sole proprietor account at a different bank just down the street, until they closed when I retired, altho I don't think my retirement is why they closed. I have a credit union account which is far away but across the street from a big mall just off the interstate which is not convenient but gives me the excuse to go shopping or eat out at Red Lobster.
My mortgage and last car loan were handled through a big name bank, but I don't know that the credit union wouldn't have handled them just as easily.
Not sure what you mean by a money center bank. Another option though if one has investments is to have a cash / checking / debit card account with your brokerage firm.
Once upon a time I co-signed for a line of credit with a big name bank for a 501(c)3 where I was a managing director. I didn't like that experience. In the end the bank was awful and I got stuck with paying back the whole line of credit out of my personal funds, which I couldn't really afford at the time.