Thank you all for the nice comments. I will definitely start posting more of my work. Some responses....
So true. I actually gave up on keeping my wife's car clean because of how tough she is on it. The tipping point was when she was loading a box into her car, left it on the hood for a moment then DRAGGED it off leaving deep scratches. She didn't think anything of it!
The process used was the Leatherique restoring method. In a nutshell:
Particularly filthy seats get pre-cleaned of grime using an all-purpose cleaner. Leatherique rejuvenating oil is brushed on to all leather surfaces and hand-rubbed in. The car should then sit in the sun with the windows up for a day. This allows moisture to be injected into the seats and contaminants lifted. The oil is then cleaned with Leatherique leather cleaner, and rinsed/hand buffed to a soft, satin finish.
The "cracks" in the seats were really just folds in the leather in which grime had built up. Proper treatment can make the grime go away which gives the leather a like-new appearance and feel.
Yep, special attention is definitely given to the high-wear areas. I actually went back and applied oil half-way through it sitting in the sun because those areas were so dry they were soaking it right up!
A couple hundred dollars including the leather treatment. If you don't have leather (and if your car isn't as dirty!) it would be less expensive.
Answered above in more detail, but yes, scrubbing, Megs All-purpose cleaner 10:1 (that stuff can be pretty serious in low ratios so be careful with delicate surfaces) Leatherique oil and leather cleaner, and more scrubbing!