Personally, I don't think it's necessary for you handrails to match your floor. Nice wood floors are sort of like bluejeans, in that they usually work well with other things. My handrails are a beautiful decorative blond wood, and they have never matched my floor. However, if your handrails/stairs are a major focal point of your room, you may feel that they should match to unify the space. In any case, it's your house and you should do whatever you think you'd like best!

Painting the cabs to a high standard is an investment in both time and money I would not do in a rental. Also, is the owner supplying the paint for the walls? As a landlord and a former renter, I would make sure that any colors chosen get the owners approval first. As to what shade could work best for you on the walls, can you share more pics? Agree with you that the current shade isn't working. And I would most likely paint out that bit of white trim to match the new wall colour, if the landlord approves.

So for painting them white - the trim and crown is all superwhite. However, the stone has a warm tint to it, which is much warmer than superwhite. BM White Dove matches it pretty well but I am afraid the superwhite trim will then make it look dingy. Suggetions?

When planning a whole home color palette I often use multiple colors. I generally use a neutral in the living room and hallways and might bring it into other rooms (dining room, kitchen, laundry, bath or bedrooms, but can also do those rooms with color. It depends on what else is the same or different. If you have the same flooring and trim throughout you can change wall color and still create a feeling of cohesiveness. In my last home I had different flooring, but used the neutral on the ceilings throughout the house and that created the flow from room to room. The key is to carry the colors from room to room, so if you use the blue on the walls in the dining room you want the neutral in the area rug, chair upholstery, art or décor (centerpiece, bowls on the sideboard. . . ). In the adjoining living room where the walls are neutral I want some of the blue in the décor. You may want to add a 2nd accent color in the living room and have that color in the foyer. What you don't want is one room that is totally disjointed from the other rooms that are in the same sightline. You want to walk from one room to the next and have the same colors, but in different ratios. You can also use lighter and darker shades of the same colors. Here are a couple of examples: I love this example where someone flip flopped the trim and wall color in two adjacent rooms. There are so many ways to add color, you just need to decide which colors make your heart sing and how you want to incorporate them into your home.