Winter Red would grow much too high in front of those Windows. Go with Red Sprite. I have twelve Red Sprite Females and one pollinating Jim Dandy male for them. My Jim Dandy is not that close to the females, I would think 10 yards would be no problem.

I really like my Red Sprites, greatt berry production and the shrubs don't grow overly large. I have them where I can see them from my home office window and watch the birds eating berries come wintertime.

I have several red sprites and one winter red. I like both varieties very well--and have separate pollinators for them. Birds seem to like the winter red berries better, maybe because they're a little smaller. There is a period in early spring when there aren't any berries or leaves on the plants. They leaf out late. They're not attractive then, so I question whether you want such a large area in front of your house with just winterberries. Maybe mix in some evergreens as well? Possiblities with berries include holly, yew, juniper.

Anne

"The bay window is about 3.5' above the soil surface"
In front of your bay window consider lowbush blueberry. Either V. angustifolium or V. pallidum. They stay low, make lots of berries in Summer and birds love them. Also this solves your pollinator problem.
Sam

What about putting a few bayberries along with the winterberry? I also have fall mums planted out in front of the bay window as well.