55-60mph unless I'm getting a lineup behind me and then I will pick up the pace so I'm not causing a problem (usually not an issue as we avoid peak hour driving)
In hilly areas, I creep up near the bottom of a hill (mid to upper 60's) and let it bleed off a few mph on the next uphill. Helps avoid a lot of downshifting.
The new truck likes it up closer to 60mph as the rpm at 55 is a little low to put out good torque and it feels like it's lugging the engine a bit unless I downshift. The old truck felt like it was at a nice point for torque by the time you got up to 55mph.