Yes, I would do a wall there. I don't care for the peek-a-boo effect of split levels with all the stair railings and would put walls wherever feasible and practical. In some instances they may be wired for TV to help with furniture arranging.

A wall on the right as you walk in and a half wall on the right side of the stairs?

I'd wall up both sides where the railing is, no half walls. I wouldn't like the feeling or experience of being nearly eye level with floor carpeting.

I would wall up both sides too but you would have to remove the stair and platform treads but are you planning on demoing the whole entryway?

You already have a half wall that the railing is attached to the top of, just remove the railing and continue wall up, the stairs aren't part of it

I’d think on that awhile as doing so will really close up & darken the landing & stairs. Can you do a mock up with sheets of cardboard or something put together to get a better feel for effects? Maybe instead consider a change of railing to full height, chunkier spindles or decorative iron rod like pieces? Having trouble describing my visual! Looks like a large & active entry. if it’s color you’re looking for, art on wall where mirror is & at bottom of stairs are likely spots as well as addition of a large rug in center of space.

It’s the openness I dislike. Straight ahead when you walk in is a sunroom with tons of light so I think it won’t be dim (took pics at night so hard to tell!)

@Larece Associates tell me more about the stairs...why would they require demo for the full wall?

i understand the sun room lights up the entry - that’s the room your little one walking into? That won’t help landing or stairway though as it looks like they’re lighted from entry ceiling light & a bit from front door sidelight. But it’s a matter of priorities- which feature you Like / dislike more or less. I’d still try to do a mockup to get a feel for the change a full wall will make. You don’t want to feel like you’re entering a tunnel whe you head up the stairs. I’ve learned to make sure I have proper expectations for results! 😌

Oh, I see what you are saying! It’s very a very short passage from the entryway up the stairs and into the living room. The wall would only be about a yard deep. Appreciate it!

If you want the wall there you have to take off the treads in order to extend it from the wall from the floor or just trim the platform tread. you don't want it sticking out.