Can you share a photo? It would help to see your space (and you may be trying to post pics as I type, but the Houzz uploader is notoriously cranky), but in general I would vote against hanging a curtain. I think it'll just get in the way and be more of a nuisance than an enhancement. Just let the W&D be and do as they were intended, and resist the urge to try to disguise them even being there.

The laundry area in my previous home, which was built in 1940, was right smack in the kitchen -- in the breakfast nook, to be precise. I had a full-size W&D (not stackables), and I always felt like they just looked WRONG in that space. At one time I considered ways to try to hide them (even considered making fabric covers for them, which would've driven us firmly insane I am now sure), but in the end just decided to let them be. These days, I'm much more likely to embrace appliances as they are and forget the notion that they must be hidden. We all have them; we all use them. And it's ok to see them.

My daughter just sold her small condo that had a washer and dryer in the kitchen. They were old and kind of ugly, the dryer a front loader and the washer a top loader. Strictly for sale purposes and listing photos, I suggested (and ended up doing for her) hanging curtains in the front. My husband also cut removable white boards to cover the tops and use as "countertops" when she wasn't doing the laundry. I have to admit that it looked extremely cute (and she sold in one day!), but she said it was a hassle to lift the curtain to load the dryer and a pain to remove the washer "countertop" when loading the washer. I guess it depends on how much you mind the hassle compared to how charming it can look.

What is the reason you want to cover them up? Is it the clutter? Style the area and find places for everything when not in use. Maybe a mounted shelf or cabinet hung. I think the curtain will be a nuisance and odd. I have my W/D in my bathroom and they are exposed, though I do have cabinets that contain the detergents and ironing equipment.