I won't be offended....
and hopefully you are not offended by my suggestions. This is YOUR home! Anything you do, I just want to see how it comes out!
As for the grey, I love it...my wife got me into it, although I typically do 99% of the designing. We went for a light but "bright" grey, if that makes sense. Grey sounds drab, but this was a very upbeat grey, not a "stormy" grey.
Grey tends to not offset anything negatively, and you have a nice print and other furnishings to bring colors in, plus the couch itself is intensely colorful, in a great way.
In the color test site (I am trying to remember it too, I thought it was Home Depot but I guess not) you can try that yellow--maybe a light one. Yellow is a funny thing, and I totally agree with you, if it is not absolutely right, it will clash like a son of a gun with the couch. My mom picked out yellow for her house, and I was shocked, but when we painted it, it looked great. Yellow is funny. Super pale green is a relaxing color, but I question using it in a living room, and you again have the same challenge of it not quite working with the couch.
I love the high ceiling. If you stay with white or grey, there are tons of things you already have that will bring color in, and you can add more.
Pete, is your carpet grey or almond?