I know someone who took the 3-day Colgate course in Stamford, CT and was very satisfied. After the course she felt a lot more confident that she could helm a boat on her own. I have heard a lot of good things about the Colgate course. I heard the J Boat class is very good, but possibly a little advanced and maybe more leaning towards racers.
Colgate''s web site is http://www.offshore-sailing.com/
They have classes in a lot of areas.