Wouldn't hurt to change the brake fluid as well since it is recommended at 2-3 year intervals. The '06 Tundra comes with long life coolant that is supposed to last for 100,000 miles. By time alone, I'm guessing every 5 years or so would be sufficient, or just for peace of mind you could always change the coolant out every 3 years. Definitely no sooner than that though. Worth noting is that the long life coolant needs to be diluted 50/50 with deionized or distilled water, whereas the newest Super long life comes pre-diluted. Might not be a bad idea also to change out the rear diff fluid to synthetic such as Royal Purple or Mobil 1.
As Yamatoy suggested, definitely flush the brake fluid.
Brake fluid is hydroscopic, meaning it absorbs moisture from the air just from sitting there (and I'm sure you have humidity in Oregon). As this happens, 2 things occur:
1) the boiling point of the fluid is reduced, such that repeated hard braking could boil the fluid in the calipers and lead to loss of braking power
2) moisture in the rubber lines and calipers can weaken the lines and seals
Other than that, you should be fine... except for the flat spots on your tires from your truck sitting so much. ;-)