I have a 06, which I have been using on the farm out here in kansas and colorado. Aside from the heavy duty towing which mine cant really do, only 6600lbs, my suspension has really come in handy. I was just thinking the other day that if the farmers out here used a little bit of offroad technology that they would be able to get more work done.
Front Suspension A good set of coilovers for when you are charging down the dirt roads and you hit the wash outs and all the nasty bumps created by the rain and big tractors. Just yesterday my coilovers saved me from bottoming out really hard. I really like the Camburg setup for coilover and UCA. The combo should be good for 12inches of travel.
Camburg Engineering Inc.
Rear Suspension In the rear you might want to look into airbags for leveling the rear when you are towing or are hauling heavy stuff in the bed. Loading pallets of minerals and salt can be pretty heavy.
Another option could be those timbren or supersprings helper springs if they make them yet.
SuperSprings - Product Guide
Tires I think tires can make a huge difference, I went through a really bad washed out road that people hadnt been on for days due to the mud, I would like to partially thank my toyo all terrains.
On an 07 I would run 35's just cause you can, you would get a nice footprint as well as being able to soak up alot more impact. Tires in a way are part of the suspension.
My truck has been all over the place, from chasing in baja to all over socal, to the midwest. I have found that this style of setup will get you through alot of places.