I think curtains just the length of the window could look fine, stopping at the radiators below. You don't see it often in newer designs but it used to be done often and there are still places where it's just the ticket.

Your roller shade picture from your other room would have less of a gap if you did not have valances so take that into consideration. You can hang drapery in the alcove for those guests that requires it or you can hang small panels on the ends and the corners only to hide the gaps and yes only to the top of the registers. Nothing wrong there as you have a deep sill. I have also seen wood pieces made that fit out of the windows over the gap with the blinds behind.

Several pairs of new sleep masks would be a nice option for your guests. Perfectly good ones are $1 at the dollar store.

Your guests get to stay for free in the city ... and they complain about light leaking into the room in the morning? Tell them you'd be happy to recommend a few hotels next time they are in town!

I love a dark room, but would never expect my hosts to spend money changing their window treatments.

Depending on how you arrange your furniture, could you do drapes straight across to close off that alcove? https://www.decoccodesign.com/blog/bay-windows

How about long panels on either end and then short over the radiators?

Radiators...can't remember the last time I heard it. Our first home, built in 1911 had radiators...steam. Wow, the best heat ever...kept you toasty and add moisture into the house.

Great pics @Jilly. I thought sill length curtains were a huge no-no but the pics you show are super charming, especially the first and fifth pics. I bet if I have them stacked about 10" outside of the window it will give the illusion that the windows extend all the way to the side.

@elcieg I do like your idea. Unlike the pic you posted, we only have a few inches between windows so I wonder if having the short panels there will spill over into the glass area and reduce the view?

To those who object to making guests comfortable: 1.) My guests include my parents. I love making them comfortable. 2.) I have slept in here and the light coming through those cracks at 6 AM is utterly, blindingly, and painfully uncomfortable. My own bedroom is not dark and I have no problem with it, but this room is like a flashlight straight in the pupils after smoking a bowl. 3.) Yep, I can have eye masks. But since I'm at the point of purchasing window treatments, I'd like to have them solve this issue.

Now on to curtain rods to fit a bay window ...

Kendrah, I read and follow so many UK and other European blogs, IG accounts, and websites … they’re so much less rigid and uptight about decorating. They’re used to working around old house features. :)

Can’t wait to see what you do, please update!

@Jilly - Can you share some of the UK and European blogs and websites that you like? (I stay away from the rabbit hole that is IG!) I'd love to explore more styles. I'll certainly post updates.

You will minimize light gaps on roller shades if you specify them as reverse roll.

Kendrah, I find most on IG first …. I just do hashtag searches of relevant terms and IG accounts and website links will come up. I agree it can be a rabbit hole! But lots of great ideas, too.

I can't really see in your pics if this could work, but would it be possible to hang draperies forward from the bay, out of the way in the daytime, but pulled at night? Like this:

If you cannot hang a rod like those above, you could hang from the ceiling:

I'm not sure where to hang the rod from as coop handbook forbids drilling into the ceiling and the wall above the window - painted blue and orange. (Structural beams.) . Thoughts?

@Olychick Because this is a studio apartment in Manhattan and every inch counts, I think it cuts off too much space to hang them across the "alcove".

Was just reading UK magazine House and Garden and loved this quote: ‘Absolutes don’t matter so much any more. Sill-length curtains were once thought of as ugly, but I just did some with a scalloped edge and they looked divine.’ Thank god for the Brits! (Unfortunately the article was followed by 35 pics of amazing floor length curtains.)

@Kendrah - what you should look for are "blackout shades with side channels". The side channels keeps the light from coming in through the sides of the blinds. See photos below for illustration.

I had an interior designer install these in one of our bedrooms that has a southeast exposure (during summer the sun comes in at 4:30 AM). I don't know brands personally, but here is a link to one that came up when I googled. If you don't want to buy online, you could look locally for a place that sells "blinds with side channels".

https://www.zebrablinds.com/blog/why-side-channels-for-blinds-are-a-necessity-01-2020-04/

@Mmiller I don't think there would be anything for the side channels to attach to except for the far left side and far right side of the window. There is no frame between the windows that sticks out beyound the surface of the glass. I think it might be why there is so much light that comes in.

Not a decorative solution , but I’ve had a video pop up about someone using suction cup attached black out shades for theit baby when traveling. They look very effective and super easy to install.

The suction cups sound pretty brilliant and great for anyone to bring when traveling.