In reply to Fraser:
Kost is good but for me, skipping to and fro between the video and Lr was a pain. Not my learning style. Kelby falls in the same category though for different reasons.
Martin Evening and (briefer) Jeff Schewe's "The Digital Negative" hit the spot for me because in addition to teaching me how to use Lr they helped me understand what the software is doing. If only one? Schewe.