I've seen a lot of people saying that it sucks that cities don't auto-expand their borders anymore. For me at least they do. It's just really slow but there is some expansion.
I'm not sure what that is about, you just build culture buildings like you used to.
It expands one tile at a time now... but it still expands itself over time.
A few of my high culture cities have expanded as far as 5 tiles out.