I ride my Specialized Crosstrail, 700X45 tires, with suspension fork locked and unlocked. I keep the tires at their max pressure of 85 PSI. It is way more comfortable when it is unlocked, and can absorb bumps, especially the sharp ones. Oddly, the steering is a little more "twitchy" when it is locked.
I really like the improved ride of the large tires, and the front suspension. It sure made my riding more enjoyable.