The Coaster is a nice idea, but totally useless unless you're a 9-to-5er who happens to work downtown. Weekend runs are so few and far between (and expensive) that you're better off driving. And God forbid you want a night out on the town -- Coaster don't run past 7pm.
Until now. The Coaster has just added new Friday and Saturday night service leaving downtown at 10:45 and arriving in Encinitas at 11:26. Enjoy -- I will!