Photos of the feature wall would be helpful.

Pictures would certain help, but "feature" doesn't necessarily mean dark, or even bright. In a white or pale neutral room, a feature wall might be grey or a pastel colour. A feature wall might also simply have a marked texture that the rest of the walls don't have, such as grass wallpaper.

On the other hand, a tall, bold feature room can look wonderful in a well-balanced room.

http://dyyana.com/feature-wall-bedrooms-ideas/teal-white-entertainment-units-and-blue-accent-wall-designs-with-paint-dramatic-wooden-door-also-futuristic-tv-entertainment-unit-bedroom-design-modern-bedroom-design-feature-apartment-design

http://search.har.com/site/19930-Brookway-Oak-Ct-Spring-TX-77379-2604_SITE61254740.htm

These are two separate rooms? Not sure I understand what you mean by sharing a wall. There is no break with wood work?

Forgot the other pics.

Sorry I don't have photos. The room is dismantled for hardwood at the moment and a complete mess. What I have is a very long bungalow with a wall down the centre of the house at the peak. The den is the only room that is vaulted and basically slopes from the peak of the house to the outer wall, which has a fireplace on it. The current "feature" wall runs the width of the house, so it shares one wall with the den and one with the family room. I don't want to be obligated to that color in both rooms, which is why I would like to move it. I considered the fireplace wall, but it is bracketed by two floor length windows so there is maybe 5 sqft of wall to paint, the rest is window and brick. Thus, leaving only the really tall wall paralel to the fireplace.

Excuse me for a minute, fyrefly75.

Rina, would you e-mail me? I have a question for you. Thanks.
http://www.houzz.com/pro/iamjudy/judyg-designs

This photo has very similar dimension so my room. The ceiling is stippled, so I don't want to mess with that. There is a walkway through the tall wall to the family room that shares the wall with the den. Its that really tall wall I would think of painting. Of course, they would all be complimentary, but I suppose this is stemming from my wall choice in the dining room and the far end of the house beside the family room. It is red. I am hoping for a rich earthy (and dark) green for the den, but am worried that having a green wall on one end of the house and red on the other will be too much. If I can contain the green to the den, I wouldn't have that issue...but then there is the worry that there would be way too much of that green for a tall wall. I'm going to take some pics tonight...you are all too helpful not to have photos to work with!

We may do better with photos, fyrefly. I still can't quite picture it. You may be worrying over nothing, too. In my own house, often I can't see the forest for the trees.

Mixing red and green is fun. Looking forward to the pics.

Judy: done. Sorry it took so long to respond.