Any suggestions how to hide this ugly intake vent?

Paint it the same color as the wall so it blends in.

You could make a radiator cover to go in front of it. You then gain a shelf too!

You could put a palm tree(live or silk), in front of it and if it doesn't cover all you want covered, add 'Words' , like Live, Love, Pray, etc... above it to draw attention away from the part that is showing. Or paint it the same color as your wall. It will diminish the white that stands out. Or add little shutters on each side and a shelf above with greenery on it... hanging down a bit. I hope this helps some.

Yes, I agree, paint the same color as the wall. You can also safely place a console table there too without restricting air flow. Then top the console table with usefull items for keys, mail, etc., and something tall and pretty to be the focal point.

You have the space so why not add a piece of furniture to cover it up. You can find or DIY something like the picture below which still allows the airflow.

Here is a great idea. It's actually a doormat that is placed over the vent. It's really pretty. I think I would do something like this. It adds beauty also.

Be very careful putting any thing in front of it. If you limit the airflow it will affect your HVAC unit.

I agree with painting the same color as the wall. I did that with the small ones in my bathrooms. Then buy a large, low plant to sit there. Good luck.

A grouping of indoor potted plants. You can use a multi tiered plant stand to achieve the height.

I believe the issue is you have nothing to draw the eye except the vent. I would suggest you simple draw the eye away without stopping the vent from doing it's job.

A table that allows the air flow to still get to the vent and be sure to have felt on the feet so when you have to move it to change the filter there will be no scratches on your floor.

Then decorate with family photos, floras, etc. WALL ART for sure, or a mirror with a beautiful frame. Be sure to have highs and lows on the table top because of the stairs. I posted photos so you can see some idea, depending different taste.

It does sound silly but I did the same as many other comments. I painted my intake the same color as the wall and it really does just disappear. Then you can enjoy putting whatever you want there whether furniture, plant, bench, etc. without worrying about the vent looking off center or odd. I always try to do the easy option first and go from there!

I would suggest a hanging Shelf with fake hanging plants that hang down towards the vent so they don't interfere with the air flow you can find a lot of pretty fake plants that are hanging and draping over down to the vent.

Have you tried a potted floor plant? Either real or artificial.

Both of the above are great solutions - be sure to NOT block the air flow or it will cut down on heating/cooling - whichever you have running at the time!

Paint it the wall color

I agree with Beachem, you do not want to block the air flow. I can tell this is an air intake vent. You need access to change the filter from time to time. Start by painting the same color. If you can match with a spray paint, that would be best. If not I suggest you get an electric spray painter. Trying to paint with a brush will not only leave you with paint brush stokes, but it will be very difficult to get the coverage you need.

Don't block it. if you don't want to paint it to match the wall color, you can put a small accent table in front of it and place taller items on top of the table to pull people's eyes upward toward the decor on the table.

A Chinese plant with lush leaves and white flower would be perfected in a nice big urn. End of search.

Buy a decorative piece of radiator screen at a building supply store and frame it out with mouldings to make it look like a work of art. Some stores will cut the metal screen to size for you .

I cannot see a photo but I imagine what you describe. Buy a rubber door mat at Home Depot in decorative design. They are open mats with raised design. Hang across the vent. Gives a finished decorative cover up while allowing the vent to do its job. I likes the idea also of a green plant if there is room and it will be easily accessible for you to care for it.

Paint it the same color as the wall to minimize the obvious, then a table that outlines it size-wise with tall art/items to bring the eye up.

You really need to add a table. A Parsons table would be narrow. You can then put a plant under the table to hide it, and then yes art above it to draw the eye up. Right now your foyer looks like a place you pass through and not part of the home.

You could paint it to match the wall, but don't cover it or block the airflow. A narrow table with a plant on that end could improve the look

I agree with painting it the same color as the wall. I would get a cute accent chair and small chair side table for the area. The chair wouldn't block the vent because you wouldn't put it against the wall.

Paint the frame the same as wall, you could put a parsons table with decor on top, or a small framed club chair angled in the corner and a floor plant. So many options if it was painted.

Build a plant stand with perforated metal so it doesn't affect your air flow. Most large hardware stores carry them in a variety of sizes. See example-

your foyer is the first and last thing you see walking in the front door, and that space is everyone's focal point when entering. I searched kirklands and they have two item that may interest you and add accent items on top and an over head mirror. They have an app that free to download it's called spin to win and you can spin it once day to receibe an extra % off on line or in store and it's only good each day. Today they have free shipping and an extra 20% off with code NOMBRSHP for today only. View the site they have lots of consoles.