You can do something like this, put a nice wood ledge and install 1 1/2" X 1 1/2" stain or paint grade lattice spaced evenly 4" OC and it will make a nice child proof opening and also a nice detail at the same time.

Plexiglass framed and nailed into place would be safe yet keep your light unobstructed.

Playpen. Leash. Spanking. Locked room timeout.

Plexiglass (or tempered glass) panels, perforated metal grilles, or lattice.

i'm with leelee, they only give a view to the other side of the stairwell. i'd sheetrock them closed and fix every single problem at one go.

How about stainglass ?

The lattice wall is a great solution and budget friendly. If you are concerned about the loss of light plexiglass windows or panels would work. You might get some inspiration from looking at various stair spindles or metal pipe at the hardware store (even pvc pipe - there are paints out that will adhere to the plastic for a great finish)

Drywall the whole wall, including the opening at the top. As it is now, you tv is overhanging the wall anyways. It will give a much updated look to a 1980 s home.

I would definitely drywall rather than anything temporary that could possibly be pushed loose by a toddler like lattice or the like. With your TV on that wall, the openings really don't work anyway.

What is a toddler recliner?

Is it puffy, have cup holders and made of faux brown leather, lol.

It's the 14 seater toddler brown sectionals that really make things difficult.

I can’t tell how much I hate toddler furniture but that said I agree with drywalling the ones that really are useles and the ones you want to keep plexi in a frame easy to do and it does not block ligh or create weird shadows

The first thing that I would do is to remove anything that your toddler can push and climb on to prevent injury , for the opening you could have custom made a couple stain glass panels to cover them up.

By doing this you wont loose any light on the upstairs .

Unless you are planning to have 5 kids, the toddler years are over quickly. You wouldn't have to live with an ugly kluge of a solution for all that long.

Just an option for thought.

The first thing on your list is the safety of your child. Drywall the unnecessary opening. There is no view, and it will be better to have the tv in front of an actual wall. Do it as soon as you can....like tomorrow. Children climb and you have a disaster waiting to happen!!

if you like the openings, just buy 2 window guards for now. He won't be a toddler forever.

http://www.amazon.com/KidCo-Kidco-Mesh-Window-Guard/dp/B009XDVSTM/ref=sr_1_7_a_it?ie=UTF8&qid=1464881826&sr=8-7&keywords=window+gate

http://www.amazon.com/John-Sterling-1134-Window-Guard/dp/B000H5Q714/ref=sr_1_1?ie=UTF8&qid=1464881826&sr=8-1&keywords=window+gate

This is what the wall originally looked like when I bought the house before I redid the entire upstairs and stairwell. 1967 the house was built.

I wanted a way to allow light into the stairwell and not make it feel so closed. Figured I'd frame it in a way to allow for the mounting of the tv (current tv is larger than the original one that was there) and yet light to pass through. Normally we'd have stuff on either side of the entertainment center but now his toys typically end up in either spot. And yes the toddler recliner is a single seat brown leather reclining chair with cup holders for his juice bottle and snacks. He was only just able to begin climbing up on our couches, so this was for him to be able to have his own seat and sit with mom and dad in the room on his own before (he's very independent). If I had to get rid of everything in the living room he could push I would have nothing left. He just turned 1 but is bigger than many 2 year olds (I'm 6'7", he's definitely taking after me) and is easily able to push our coffee table around the hardwood floors without a problem.

There is a great paintable product out there called Out Deco ( www.outdeco.com ) lots of designs and styles to choose from - you could definitely choose/paint something that would work with your space - and keep your kiddo from going head-first down the stairs.
Good luck!

I'd put a vertical painting on each side hiding the hole for now.

Paintings will look not good from the stairway side.
Maybe drywall the two openings on the sides of the tv, then leave the opening at the top for light. It will give you much more usable space too.

You made a good effort, but I think didn't achieve your goals. I'd close up all three holes and then add some wall sconces in the stairwell to brighten it. Both rooms will be better in the end. No shame -- we all live and learn.

I feel your pain!:). I have an 18mo old climber and 2 sets of stairs!! I found her on the outside of the banister at the top of the stairs last week!

I think the best solution is to enclose them with drywall. Even though toddler years are just a phase, what about future children? Or your child's visiting friends who have even less restraint? The openings really don't add anything to the wall other than a danger or an opportunity to pitch objects through them.

If you didn't want them closed over, what about some wrought iron decorative screen. I would go to someone who makes screen doors and ask if they can make something for you, might look quite effective without being to much.

Whoops pics for above comment

I think it would be best to drywall the open areas. The current tv slightly overlaps the cutouts which looks odd. Unless, you use a smaller tv in this spot, any decorative fillers (plexi glass, wrought iron, etc) will look busy and unbalanced. I would put the safety of your little climber first. Drywall. Your family's needs have changed, your house needs to too. I think future owners would prefer the area closed too. It is limiting for furniture placement.

As far as light in your hallway. Change to a light colored paint ( Benjamin Moore Classic Grey would be nice), hang a large mirror above the ledge to reflect the chandelier light, increase the bulb wattage to the maximum for your fixture. The yellow color can actually make your space darker and drab without adequate natural light.