Los Angeles: Griffith Park bike lane. A good place to start is from the North Zoo parking lot. For classical it’s up and back a little over 2k each way, with lots of gradual upgrades. More adventurous skaters can ski the whole park loop, which is about 3-4 miles.
Santa Monica (West L.A.): There are a few streets in good condition wide and long enough and without much traffic between Montana and San Vicente Blvd. Not the best but workable. Wear a reflective vest. – G.G