For films, you'll want as much darkness as you can get, but as you say you usually watch films at night so hopefully not much of a problem.
For regular TV, esp Sports you can get away with a fair amount of uniform ambient light.
What you really have to do is avoid any light shining directly onto the screen, for example I use directional halogens and some diffuse lamps that sit behind the line of the screen, this gives me good light and watchable football
So for the skylights you will want to be positioning the screen so that the sun cannot shine directly onto it (preferably at any time of year

).
-- Jon