Wait until you furniture is in the room. A blind may well be best for both windows.

This is actually an old picture from when my home was listed on the market. It has been furnished for several years but I don't have an updated photo at the moment. I'll try to take one when I get home.

There's not enough room inside the nook for curtains. You could do nice roman shades. I've bought some for bedrooms on this site that are quite nice and budget friendly. Let me know if you'd like a link.

I guess you could do sheers over the shades, but hang them outside the nook? Not sure if that would look strange, but maybe you could mock it up to see.

I “liked” lupins' suggestion.

You, also, could use the same panel material which is on the other window with a different treatment, like this inspiration photo, adding a small bench in the nook to make it a bit special. Different windows need not be dressed the same, IMO, as long as the fabric is the same.

A bench is a great idea!

What do you have in the nook right now for furniture? That determines the draperies. I really like Roman blinds for a bedroom and they will suite these two windows beautifully. If you put draprey panels on the outside as well, and have a bench built into the nook, you would just shorten the drapery panel.

Some great ideas, thanks everyone! Currently both windows have plantation blinds and nothing more. There is an elliptical machine in the nook, which is going to go. I love the built in bench idea!