When looking for a sail school, or a sail club for that matter, look at the condition of the boats. That is an excellent indicator as to how serious the organization is regarding their dedication to sailing and sailors.
I have been with my San Diego sail club for 9 yrs now. Just putted around for the most part, but finally got serious and took my coastal nav and bareboat this past month. Bareboat was a great experience and I learned alot in 2 days at sea. It also solidified what i'd learned in the past.
As to nav? It gave me a headache, lol....but is a vital tool when cruising, which is what i plan to do. Since anything can happen to a gps unit, nav skills can save your boat and your life. Don't ignore it.
good luck and fair winds