First sketchup try, request design input & color ?

Hi, here is my first try at using sketchup. This is the end wall of an upstairs bonus room, with a window in it. I want to put some "built ins" up against it, with space under the window (64") for a sofa.

1. In sketchup, I've colored all the walls the cocoa and beige of the real room, but I can't get them to display right! At certain orbit angles yes they look correct, but in this head on look, the cocoa back wall behind the bookcases looks orange... I want to be able to show truer colors so I can make some design decisions on wood colors and contrast, how can I force it to stop auto-coloring the planes different than what I apply?

2. Design ideas: I had planned on using maple veneer plywood for the carcass work and face frames of walnut--I'm tryig to create a beige/brown contrast to play off the similar paint scheme in the room-- right wall and back wall behind the bookcases is cocoa, left wall is almond/cream/gobi desert. Furniture in there is sofas up against the dark walls that are cream, and maple picture frames on the dark walls; and an espresso painted TV armoire against the left cream wall... you get it, the brown/cream contrast.
---Will walnut faceframes on maple ply look "wrong"? That is, will it look odd to not have the same wood as the hardwood edging? Or would that contrast be acceptable and nice?

3. "Built ins" vs. bookcases... I had planned on building this as 3 units, then fixing them in place against walls, and trimming out edges and columns with scribed fluted verticals; and crown molding on the top. Should I put a back on the system, of 1/4" maple ply? Or should I make it just boxes that show through to the cocoa wall behind? I'm not conversant with the impression of each method, and whether it is considered cheap or informal, etc.---some thoughts?

4. Balance: the wall is 156" wide and 95" high. The right and middle case are 27" wide, the left one is around 38.5 " wide. The left bottom is open, I was thinking about making it a "desk" for my 4 and 5 y.o. boys to do computer stuff at...wife tells me 2 separate stations will reduce arguing ;)
a. How do I balance it? Make the cases on either side of window match and the left case be different, OR make the two on left both match and split the left side in half, making two desks 33" wide there and balanced...but now the right side is different.
b. I planned on making some shelving as display cases, with 2" torsion shelves w/ embedded lighting. If some shelves are for books and some are display, what is normal? Which do folks usually use for display and thus light up, the tops?
c. If some boxes were covered w/ frame/panel doors for covered storage, which would you do?

Thanks for any thoughts, this is my first whole-wall "built in", and I've searched the forum but not seen one too similar.

Answers and opinions, keyed to your numbers...

1. I've never found a way to nail down the colors in Sketchup. They modify the colors to help create the 3-D illusion, and seem insistent on doing that.

2. Face frames from a different species than the carcass doesn't "look wrong", at least to me. That's a taste decision for you to make. You might want to mock it up with real wood before you commit to the whole wall. Get some of each of the proposed species, put your proposed finish on them, and hold them up in the room.

3. You can do backless cabinets against a wall and let the wall show through. However, if you ever repaint the walls, you'll have to paint the wall inside the cabinets without dripping. Backs also help keep the boxes straight while you build them and install them.

4. The space below the window looks like a great place for a desk. Could you put just one wider one there, and not get kids fighting in it?

Jamie, thx for the input!
Good idea on the desk under window; my only concern there would be how is it to work at a computer with a light window behind the screen? I haven't tried it, but assumed it would be glaring and painful... may have to move my desk around in office and give it a go.