I would vote for the extra upstairs space, especially if all six beds are occupied. I know you did not ask, but the bathroom area makes me clautrophobic with all of the walls and little enclosed spaces. I think the bathrooms can be designed to feel more spacious yet still give privacy for 6 to use. Also, I would make the laundry area open to the hall. The two door entry from both bathrooms "wastes" wall space that could be used for a folding/sorting counter and takes space that could be better used by the bathrooms. This is all just my opinion, and I understand if the design works for you and your family.

Yes, to your first question. You can see the lower TV room ceiling here and how it opens to the foyer. That walkway measures 47" width ( including future baseboard.) I thought a post against that wall would balance the newel on the other side and allow for a "separation" between spaces? I don't know what the color should do in this area? My husband wants the darker brown for the TV room. Also, our color "cocoa" drives me crazy- it goes pinky (flesh beige) with an east facing window light-(the picture below was taken this morning) and goes blue(brown) and relaxed in the evening with sconce/lamp light. I love the color in the evening. Most mornings, I think I need to repaint! Thanks for your interest.

Will you share a picture of the space? Neutrals are tricky and mixing cool colors with warm floors or trim or furnishing can backfire. It all depends on the space and how the colors relate.

If acoustics are your prime concern, you may want to consider adding sound attenuating insulation to the two room walls flanking the stair and hall, making sure that the walls are well sealed top and bottom, that any outlets are sealed around, and that the doors are well fit. A wall next to the stairs, especially without insulation by itself isn't going to do a ton to stop noise transmission as the stair is still open on the ends. Does this stair have an open rail at either side of the main floor, and on which sides (same side as the playroom or the hallway). That will figure into how sound will travel. As with Virgil, I see that there doesn't seem to be any accommodation for a wall in the plan. Was the floor framed so that there is enough thickness to align a wall with the linen closet? And if so, does that make your stairs narrower than they are drawn? From an aesthetic standpoint I would rather have a half wall or open rail. Both hall and stair will seem very closed in and dark without some sense of openess. For that same reason I would seriously consider having a window at the top of the stairs to light the hall and stairs during the day. Otherwise you are going to need to be turning on the stair and hall light every time you pass through there for safety.