I haven't read Margulis' "Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace" book but Lee Varis credits him for pointing out what can be done in LAB. I am pretty sure that working in YCrCb or HSV will really give you any advantages.
Varis' "10 channel workflow" is essentially an RGB workflow with localized color editing. Varis' (maybe Margulis' too) big idea is that it is contrast that creates a feeling of depth in a two dimensional image.
Varis' process involves first doing the heavy color correction lifting with either R,G, or B channels as layers utilizing some very finely tuned (to the image) clipping masks, duplicating a flattened version of the RGB master and converting it to LAB, using the A and/or B channels (once again depending on image content) to once again create adjustment layers, copying all of your work in LAB to a new top layer and adding that layer to the original RGB version ( adding it to the RGB image layer stack converts it from LAB to RGB,) and then to correct for the over saturated result, making a second flattened duplicate of the RGB document, converting it to CMYK and then just using the K (black) channel to add black back to colors that are now overly bright and over saturated.
it is a lot of work and requires a lot of practice and trial and error to determine what really looks right make it work well. It is very easy to go way over the top with it.
Much of this can now be handled in ACR 5 and Lightroom 3 and 4, so I use it only as a last resort and my experience with it over the past year tells me only about 2% of photos truly benefit significantly from it. Start with the idea that just because you have all of these tools available doesn't mean you always need to use most of them. As the carpentry based saying goes: "To a hammer the entire world looks like a nail.
It also does not take the place of good raw processing discipline, a multi step sharpening (capture or input + creative sharpening based on image content + output size, method and media characteristics) and if needed noise reduction workflow, and what Mac Holbert calls Mid-tone contrast enhancement ( a very simplified version of Holbert's Mid-Tone Contrast Enhancement is the basis of the Clarity control in ACR and Lightroom.
You will also learn a lot from the John Paul Caponigro and Mac Holbert Fine Art Digital Workflow DVD tutorial: http://www.johnpaulcaponigro.com/store/dvd-fine-art-workflow.php
- It is well worth the money.