Sorry, I did not see this post for a long time. (My son, takes up a lot of time.)
Probably the best advice I got from Deke about channels is the dreaded calculations command. Now, a lot of people see it up in the images drop down and wonder what the heck it is.
Well, if you take an image that has high contrast in two of the color channels, but cannot really choose one that is greater, a good technique is to copy both, then use the calculation command to "combine" the two. Usually, if you play around with the settings in the command, you can get something that has a lot of contrast so you can then take it to your curves dialogue.
It is at that point where you really get the great selections. See, without that command, the channels panel would only really be useful half of the time.
I may get some time here in the next week or two to get something going to demonstrate the command to you all, if there is interest. ;)