A rental or your home ? I see nothing to drive that blue wall . I use cable lighting for this type of issue often but you need end tables table lamps and a floor lamp and those will give you some great levels of lighting but the beams have you having to either do the cable or track light to really get good ambiant lighting . If there is away to get into the attic space then yu could do pot lights .This is cable light it works well in this type of space you can get it with heads that you can hng lower in some spaces and next to the ceiling in others A good lighting store can help with theactual layout.

Thanks. Its a rental. I am leaning towards track lighting - pluggable unless the landlord agrees to hard wiring. Table and floor lamps by the yellow sofa and/or sconces on the blue wall.

Any suggestions where else can table/floor lamps go in this room?

You can't stop painting the wall and leave 1/3 a different color. Paint the rest of the wall. It's pretty dark, so it's going to 'eat' light.

Select the rest of the items for the room so you see how much light you really need.

Don't forget you can always add battery operated or corded plant lights in the base of your trees for additional lighting.

Lamps from Crate & Barrel.

OMG! thanks for the visuals and lamp ideas. Like the trio lamp!

I agree with the suggestion to paint the entire wall the blue, including above the stairway.

Continuing the blue wall on the left down to the entrance make the room look so much wider/bigger, go for it!