Depending on what sorta money you want to throw around a PC-12 would be a winner if you could talk them into a single. (relatively fast, up to FL300, comfortable, operating costs are pretty good) . . Failing that then probably B200 would be a winner over that sort of distance. But again it all depends on how much $$$$ there is around. If it's going to be a contracted job with xx amount of hours per month then must go turbine of some description. Cheyenne 2 would be another option but not real sure on operating costs etc