I don't think you need to brighten the room further. if anything, perhaps you need to add dimension and darken some of the tones so that the pieces you collect and love stand out. I would be careful to not cater too much to one style or collection. It could cause the room to lose its sense of purpose and cohesion.
Paint is an instant and inexpensive way to transform a room. This eggplant color (it's Kalamata from Benjamin Moore's Self-Priming Aura Collection) will bring a richness to your room and set off your pieces beautifully. Plus, one coat is all you need so if you don't love it. you can easily paint over it.