Would you recommend any of the weeklong grant writing workshops?

I am new to For Grant Writers Only and appreciate your willingness to share knowledge and experience.  Although I have written and managed a number of grants over the past twenty years, it has only been part of my work in senior services/human services.  I am currently transitioning to focus more on grant research and writing, and trying to determine the best ways to develop my skills.   To do this, I have been listening in on the Foundation Center webinars as well as developing proposals on a volunteer basis in a new area for me (environmental).  All in all, I am not really a 'newbie,' but not an expert either.

Would people recommend taking any of the weeklong training sessions such as the ones offered by AGWA, The Grantsmanship Center or The Foundation Center?  If so, which ones are the most helpful?  Many thanks for your thoughts on this and any other suggestions, Debbie Stein