To be honest, I wouldn't even consider a truck stop... I would think about some more truck rest areas. I personally don't like to stay at a TS as it's a money trap, but if I could invest in 2 or 3 truck rest areas, I think that would be worth more in the long run. Maybe make it something like the service plaza type of thing on I-80 in Ohio I can shower and fuel on the go if I need to, but it's a place to shut down that is stressful, so pretty much anywhere along the 95/85 corridor from NC to NJ and I-81 from TN to upper PA would be most helpful.
Anywhere in North Carolina. I love calling NC home, but this state is a complete wasteland for good truck parking. Also, anywhere northeast of the nation's capitol.
I'm surprised no one has mentioned Oakland county in Michigan. There aren't any with decent parking between Flint and the Detroiter on 75. I could see a nice one at the site of the Silverdome, once they tear it down, with room for 200 or more trucks. Maybe $5-10 for parking, and a decent fee for weekly parking, to keep out the riff raff. Pontiac could definitely use an infusion of cash.
Having the money is only half the problem. Having community councilmen who'll allow a truck stop, and local/state officials who will grant the few dozen required permits is the bigger hurdle. If so ... east of Seattle near I-90 and hwy 18, or in the Allentown/ Fogelsville PA area
Out in mccaran Nevada on USA parkway by tesla Apple Walmart and many other warehouse there is only a small gas station there so a truck stop at a large hub like the would make a killing
One near Seattle, WA. Tiny T/A is simply not enough for traffic that flows through there on I5 and I90.