Option 4 is most MCM look. I wonder if you could replace glass in existing doors for more privacy such as “Reed glass”. Or sometimes called “fluted glass”. Much less costly improvement. Then paint doors and framing in a line green color.

“Lime green”

Or MCM Color of your choice. I like linear glass panel too for your home.

They're all fine for style. I like # 3.

Note? You WILL very much miss the daylight. ......even the view from inside.

I'd consider a more private glass, and a deep wood tone, before I let my light go. Just sayin : )

https://www.sunmountaindoor.com/details/door-glass/

I also like #4, but I also agree that different glass and a new color for your existing doors would work.

I like #4 but not sure how it would work with the existing sidelights. Probably OK.

What 'I' would do is explore replacing the IGU's in the existing doors, replacing the locksets with something more modern and painting.

I would think long and hard about reworking the entrance and losing the double doors.

Although I like the style of #3 I think the loss of sunlight will be surprising and not in a good way for you. Price out changing your doors inserts to a different more private style of glass.

Is it possible to paint the door to a more MCM color?

Option 3 looks really perfect!

Maybe it is better to consider some other colors, but option 3 fits the best!

I actually like the original best. I would probably paint it, change the handles to something more modern, and frost the glass.

Why not price out the option of replacing the glass in your current front door and side lites vs. a new door system? The current doors suit it. A change in glass might be all that is required, unless the seal on the windows or doors is broken or the mechanism doesn’t work. You can always replace the handle, etc.

Option 2 with ribbed glass panels would be my choice, but I would probably do a single, smooth door and larger sidelights

I presume you'll be keeping the sidelights so I wouldn't go for #3 with also vertical glass in the doors.

I really like #2 with horizontal glass or #2 no glass.