On many of the flights I used routinely you can (or used to able to) get it as part of the onboard audio selections. I know United and American Airlines always had that option on coast to coast non-stop flights - music, movie, or ATC. I actually find ATC more relaxing when flying than I do music or movies - there is an added sense of situational awareness that's comforting for me. Those not familiar with ATC comms would likely find it cool for about a minute and then be annoyed by it.
It's easier to do with the piped in system as you don't have to dial in the new frequencies at all the center and departure/approach/tower/ground control hand-offs. Using a laptop is something that would work (there are sites), but I suspect frequency changes would be cumbersome. Some aircraft do not have the capability to pipe ATC into the onboard entertainment system and allowing passengers to hear it is pilot's discretion as best i know.
Scanners can be hit and miss at picking up the ground side of things in an aircraft at altitude, but you'd likely hear the pilot's comms quite well. Having a scanner in today's (post-911) world would likely cause paranoid behaviors from the crew and/or other passengers. There is a smartphone app I believe that does work well and would be a better option than a scanner (assuming the aircraft has WiFi).