I guess even gravel in and of itself has a broad scope of possible conditions so that's a tough question. When I ride gravel I just ride my normal hard tail with my normal set-up. If I were going to change anything, I'd put lightweight tires on and run a relatively high pressure. I might change to a road saddle too I guess, but that sounds like a lot of work...
I recently did a moderately long gravel grind on my old Rockhopper SS in northeast Kansas while I was visiting my parents. No computer, minimal tools, no plan, no knowledge of the roads or what each corner had around it. I saw a lot of old barns, fat cows, and empty beer cans. It was a pretty damn fun bike ride.
If you haven't already, check out some of the articles on the DK200 from this year. It was more of a tough mudder than gravel grind...gravel is a really cool niche in the sport and I hope you find your set-up. But honestly, I think the simpler your set-up and the closer you go to your normal set-up, the happier you'll be.
N.F.S. Certified Sawyer & Greensfelder Sawyer
SS Rockhopper "Black Pearl"
Specialized "Blackbeard" Crave
GT "White Lightning" Zaskar (2013-2014)