NC has some nice planes, I worked for a competitor that sorta took a bunch of their work(the customer wasn't happy with some cancellations on the nightly routes). Besides that I know they have some C310's, barons, C421, and I think a King-Air. I never heard any complaints about Mx from their pilots, seemed to be a good outfit with that in mind.
I don't know too much about Central Air except those guys worked hard! I honestly wouldn't want to fly a twin-commander in the winter, but that's just me.
Pontiac Flight Service in PTK is one that if you get your CFI, you can work for them, and also sit right-seat in the C421's and Be20's part time. I think you need to be more of a full-timer for that position though.
My company has a salesmen up @ GRR, and occasionally we need ferry pilots, but this is extremely limited flying up there, and usually turbine equipment, so restricting that flying even more to higher time pilots with time-in-type experience.