Here is a recent post from Recording Hound that concerns using control automation. I hope this helps someone. Feel free to comment!
 
Recording Hound

Good stuff, I look forward to reading subsequent posts on MIDI controller automation, I think this is something that confuses a lot of people (including myself at times).

What's the point of these four bars (phrase, lick, etc)?
 
Who is the boss, why are they the boss, (and if they shouldn't be the boss, you have some tracking issues)? There can, and often should be more than one boss.
 
What, in the context of the section (chorus, verse, bridge), AND in the context of the piece, makes those 4 bars work, in the raw audio tracks as recorded?
 
What ONE THING can you automate to intensify that?
 
How much should you intensify it to get the most out of that real estate, WITHOUT disturbing the structure and progression of the section? Of the piece?
 
Execute.
 
Rinse and repeat.
 
Its as simple and cold and mathematical as that...
 
...unless there's magic in your music.
 
And there should be.
 
But it's still a good place to start.
 
:-)

I record a great deal of solo and duo work. Automation of volume, and in particular simple effects like reverb and delay, are almost a given. They give, what could become a very monotonous delivery, an organic feel that allows the song to take you on a journey. Automation allows you to really emphasise the highs and lows of that journey, to help draw the listener into the song with the performer. There would not be a single song that I've mixed that doesn't have some form of automation on it.
I consider automating a mix a lot like acting on stage, the actor must often over emphasise a lot of their lines and movements in order to create a "larger than life" performance. Otherwise it will seem dull and lifeless to the audience. Automation is just like those emphases' that actors use as a means of bringing their performances to life.

Great points to ponder guys. I think many of the more seasoned mixers use automation as second nature.
 
One thing that I have tended to do is use automation in an additive sense,when maybe the music calls for subtractive automation. Bringing certain parts up when it might be more beneficial to bring other parts down.