I have used both stations, and would advise using a taxi. Bus conections may be possible, but would undoubtedly involve a transfer. I have arived in the middle of the night at Charlotte and taken a cab over to Greyhound, which was fine. I have also arrived in Charlotte by Greyhound and taken a cab to the airport, which ran about $20 ( over 5 years ago. ) I have used a local bus to get from downtown Charlotte to the Amtrak station late at night, which was also OK. I parked my car for several days at Greensboro about two and a half years ago, which is in a more out of the way location. I believe that taxis met trains there, or most certainly the agent could give a number to call. Hope this helps.