Trying to decorate a small bay window area.

There are window films that allow light in but not prying eyes. Sort of like frosted glass you see a lot in bathrooms. Places like Home Depot have lots of patterns to choose from.

Use a film that allows light in but keeps the sun and seekers out

You could get some pretty lace material, cut it to the inside measurement of the windows, adhere it to the windows using liquid fabric starch for privacy....change up the valance or replace with curtains

Can you use a tension robs and go with cafes?

You can bypass curtains altogether by using contact paper that has a design and looks like frosting!