I live in U-City, but not near the Loop, near the public high school. I think most of U-City's single family homes are NOT in the Loop, which is a long street with very ethnic restaurants and shops. The Loop is very diverse & businesses-like but that's just one small part. During the day the Loop is family friendly but at night, it's more of an adult crowd (lots of bars).
U-City has had its share of bad luck recently with both a fire fighter and police officers shot & killed, however, not too long ago Kirkwood (also a good neighborhood) had multiple people shot & killed. You can never live in a 100% peaceful neighborhood. Some places, like Clayton, have much better PR & you never hear about their problems, but it doesn't mean it isn't happening. Every place is going to have it's dark history, U-City's just happened. Before this, there wasn't an officer killed in 30 years!
U-City, where I live, is not at all the business district that the Loop is, and is quiet and very family friendly. There's a reason why we get 300+ trick or treaters here every year! It's great place to live! Lovely parks, people out exercising, walking dogs (even a dog park), beautiful tree lined streets. My kid isn't old enough for school & I have heard a lot of mixed opinions. Seems to me most kids start off going to public schools, but then in middle school, they transition to private. I don't know why, although I could guess. I've lived here only 2 years & every time I ask other parents, I get a variety of reasons, some want their kid going ivy league, or in a super highly challenging environment & others simply say the high school isn't doing as well as they'd like.
I've been in the suburbs others have mentioned and if you're looking for diversity, culture, and affordable living, nothing beats U-City. It's perfectly located & it's troubles are not unlike all the other cities near St Louis.