Off the top of my head, these are the recommendations I would make.
Becky Biser - Works for Tarrant Baptist Association as a director. Anything she teaches/speaks on is worth hearing. She is just that awesome! She heads up leadership development for the TBA; but she knows SO MUCH MORE!
Nancy Ortberg - you can hear her preach here: http://mppc.org/series/soul-o-lo-gy/nan ... ll-my-soul
. I first heard her speaking on spiritual disciplines.
Jay Harris - works for TBA as a director (associate of Becky B.). He's great! Especially ask him about rest, or learning from the Lord, and developing leaders.
If you can get them:
Dallas Willard - spiritual disciplines, Kingdom of God
Richard Foster - spiritual disciplines
Bob Roberts Jr. - Missions thru the front door, church planting, leadership development, ministry in the 21st century, Global Christianity.
If I think of more, I'll let you know.