Frankly, all those recommendations of gray dismay me. Gray sounds like a vile color for any room in a house. It's such a dead color.
I love mixing shades of purple, violet, lavender, periwinkle and so on, so a pastel purple or violet with maybe white would be my first thought.
A soft celery green is another.
If you want to brighten it up some, a baby yellow would do it. Or use a gold or amber for a more restful, but still light, look.
Someone mentioned combining the violet with a light blue. That would give it a soft, cool look and feel.