I'm a massive fan of public transit, however, as an American this means I can only live in a handful of cities, but it's worth it .
When I lived in LA I was miserable, driving to work every single day, driving in a city is not enjoyable. So I moved, but it's impractical for someone like me to ride the bike to work. My office doesn't offer gyms, and I can't bike in sweating.
As for safety, riding the Metro can't be beat. The worst of both worlds is our current system where bikes compete with cars for a limited set of roads.
If I could build my own city from scratch, I would ban all cars completely. Design something like a 5 mile circle, and build upward. 24/7 slow metro lines allow for commutes within the city. Then have side walks and bike paths covering other commutes. Have every pathway so well lit, 3am is as safe as 3pm.
Then have garages on the city outskirts if you need to own a car to commute out of town.
I can imagine this already existing in Europe. Amsterdam felt very close.