do you know the size of your baseboard and crown moldings? That would be my starting point. I have arched top windows in my sunroom. The base of the window sits inside the baseboard molding. Meaning that the baseboard molding comes up above the window molding. The crown molding touches the top of the arched window molding. Overall, it looks cramped. I'd figure up the molding heights for the base crown and your windows as well as the spaces between the windows and then see how much space you have left.

From your picture it looks like the lower windows by the fireplace are about the same height as your side windows. Could you put the same curtains/shades/drapes on these windows and put a blind on the top windows by the fireplace. IMHO the curtains should be all the same in one room.

If we’re talking only about the lamp and where it lands under the window, I think it’s fine. What may be bugging you however is that the majority of the furniture and decor are concentrated in the middle third of the room, like an island, and the lamp seems like it’s the culprit. You have a nice palette and furniture, post more photos of the room and tell us how it’s used if you’d like layout suggestions.

I would simply go with taller windows/doors. Transoms will make your ceilings appear lower as well as make your windows appear to have less height. Here’s an example….I took a pic of my kitchen….all the windows have transoms. Now compare it to a photoshopped version with no transoms but with simple windows taking up the same space. To my eye, the windows without transoms look much taller as do the ceilings and the entire space looks more open. If I could have a do-over, I would omit all my transoms but keep the entire window heights the same. So my advice would be to definitely do taller windows overall, but without the transoms.