I've drive both a 379 Pete and also a T-2000 Kenworth, both have their strengths, it is just what you want to do.
I would go with a 475HP, (With a 13 or 18 speed so you can uprate the HP) or 550 Cat.
Other opinions on these, 379/W900, traditional styling, at least a 265 in WB to ride right and tall sleeper, KW 84 inch studio sleeper. These ride pretty well, but the cab is somewhat narrow but still a great truck. Though with the long wheelbase it does take a little more room to manuver these trucks. BUT, if your good enough, it doesn't matter.
T-2000/389 These have a wider cab, taller sleeper, setback front axle, somewhat more aerodynamic. Same powertrains as 379s.
FYI, if your going to travel the 48 states AND Canada, you can only have a 244 inch WB truck, keep that in mind.