I watch TV from my TiVo on a 14.1" in coach. When someone reclines, it can be difficult, but since I'm not typing generally it's okay.
The trick is not to use the tray table. Use the computer on your lap. Since that's a few inches lower you get the extra space.
As far as working goes, the biggest problem for me is when someone is when there is no empty seat next to me. I can't type at all with my elbows tucked in front of me. But if that seat is open, it's okay. But that's also on my 12".
On a flight into Atlanta Monday, I was in a bulkhead window and someone was sitting next to me, so I was scrunched into the corner. I got about two hours of work done on a TabletPC in Tablet mode. Of cousre they forced my eamil recipients to read my handwriting, but I did get to bed earlier that night.
Cromely.