The Venice beach bike path is a "standard" mixed-use path. Wide enough for bikes to pass in opposite directions - total width is a bit wider than a full size pick-up truck. It's fairly twisty and bordered by sand on both sides, so if you run over the edge, you probably fall on your face.

As for appropriate speeds, a jog is about 5mph. That sounds reasonable and safe for a small-wheeled scooter. A townie/cruiser bicycle will do 10mph without too much effort, so that could be the upper bound too. Much faster with those small wheels seems dangerous regardless of location.