I went to a week-long quilt camp with Marsha McCloskey. She teaches feathered stars, but included so much more about drafting, etc. that has been really helpful on other projects. I liked her teaching so much that I took another two-day class from her eight months later.
Did a two-day paper-pieced feathered star class from Paula Golden at our local quilt show last year. It was a little too advanced for my skill level at the time.
Attended a two-hour color class from Jinny Beyer.
Finally, a six-week long Illusions class through Quilt University taught by Karen Combs. That was a really good way for me to learn since one concept was introduced each week for four weeks.
I've signed up for a free-motion quilting bootcamp in October with Harriet Hargrave.