From TrainingPeaks log and Strava, the path along the beach is .81 miles from the Marriott to Four Seasons, 1.21 miles from the Four Seasons to the end of the side walk at the Marina, and .5 miles from the Marina back to the Marriott. One loop was around 2.53 miles according to my Garmin. If I remember correctly, the loop by the Marina was under construction. This was June, 2017
The sidewalk is at least 6 feet wide.