You might want to first check out our three sponsor coaches: Jennifer Meyer at TriSmart, Paul Schon at Iron Brick, and Samantha Murphy at Evolve (you can get to their respective websites via the link below). All three offer swim-specific instruction and a discounted rate for Club members.
The YMCA is also a great central point of veteran swim instructors who specialize in swim team skills and possibly triathlons. I am a member at the Wildwood Y and we have a Masters Swim class that is taught by a coach that does do Iron Mans. I haven’t been able to get involved in it myself, but it is there as a great resource.