I used to ride an early version of those paths in the '70s when I lived in Santa Monica and dated a girl in Laguna Beach. Haven't seen them in 10 or 12 years, but she's still down there (we're both married to other people, but have stayed in touch) and rides them with her family...
In a weird geezer moment, I just realized that both of us have kids older than we were then.
I love the idea of the paths, and wish more cities had 'em. Even as an enthusiastic cyclist, though, I wonder if it makes economic sense. Budgets are so tight and bikes are so marginalized in most places that it's a hard idea to sell.