I'm no rocket surgeon, but there's plenty of information available about tire pressures and why/why not to run nitrogen. Here's my $.02..
Maximum tire pressure is directly related to maximum load capacity. Lower your tire pressure and you reduce the ability of that tire to carry the rated load. If you're not concerned with maximum capacity, that opens up a whole range of tire options.. however, I prefer the E rated tires, in the stock size, which require 80 psi for max capacity. Tires are expensive and I want the longest life I can get out of them so I stick with 80 (truck and tire mfg reccomendations).
On the nitrogen note.. aircraft operate in temperature extremes. At 10,000 ft the temperature is 23F, 30,000 feet the temp drops below -60F. A jet waiting for takeoff might be sitting on 100+F tarmac. It makes sense for them. I would think it would also make sense for an OTR truck that cruises from Death Valley over the Rockies weighing in at 80,000 lbs and needing every bit of load capacity. In an old beater that you use for around town business the nitrogen looses it's attraction to me. It's a heck of a lot easier to just put plain old air available at most gas station and service centers.
I just bought a set of Pepboy's specials for my truck that will be doing some light duty towing. $340 for the set (285/75-16), $20 shipped straight to my house. They're 40,000 mile tires and the jury is out if I get that mileage from them, time will tell. My purchase wasn't entirely based on me being cheap.. I just feel that there are safety standards set for tires that even the cheap ones have to meet. The Futura's are Cooper's just branded for Pepboy's exclusively.