This would look beautiful with a decorative curved cornice going right across all windows...will give them some colour, and pull them together. With the right window treatment expert, you will have a beautiful treatment in no time!!

The wall is curved.? Depends on what your budget will be for this window. Ideally a custom curved rod with pairs of panels. On the other end of the budget would be individual shades, relaxed Romans perhaps. You need fabric there and color, and softness that panels would provide.

If you went with fabric shades they should be outside mount and abutting each other ona flexible or curved head rail.
I think drapery panels would be preferable here.