Dear God, how big is your lap top?? I have never seen a laptop case with wheels.
They generally dark colours because otherwise you might as well spray paint 'steal me' down the side - I wouldn't even buy anything that looked like laptop bag at all actually. Why not just a small wheely suitcase?
I have folders etc to carry - I saw a woman with a red one and now I'm on this mad hunt! In John Lewis they call it a 'Mobile Office' bag. I want something girly because I facilitate training in women's stuff. They had a Kipling one in JL but it was grey.