This room is perfect for an accent wall color -- you're right. I've done them with great success. Color is my "thing." Based on your photos, I'd go for a gorgeous blue and do not aim to match your rug color -- won't be identical and not enough depth if they are. But do go for something that looks great with it. I'd go for a really rich hue since everything else is white. Guarantee you'll get tons of compliments and smile every time you look at that wall. Keep it mostly spare, not crammed with art so the color does the talking. For starters, I'd put it right smack on that wall behind the small couch next to the kitchen seating area.

Another thought is to go with your red accent color -- I love red with "off" blues like turquoise and your teal. I'd make it a deep, rich red. Glad to look at swatches if you want to send. :)

P.S. I wouldn't use the same accent color in multiple locations -- especially if you're going with a dark, rich color. So one option is to use a deep teals blue on an accent wall in the kitchen and a deep, rich red on that wall next to the seating area. I'd consider painting that whole "unit," including the sides left and right where the closet door is (but keep the door white). It'll look like a little secret treasure area.