Great looking quilt. I would be tempted to match the colors of the various pieces, but the off white would look good as well.

Have you considered variegated thread? I think your quilt is beautiful, by the way!

That reminds me, I purchased some variegated thread... but have not yet found a place to use it.

I think if you are a confident FMQer you could use the same color all over, but for me (since I am still improving my FMQ skills) I tend to change my thread color in areas of my quilt where the threads are not so much of a contrast.
Good luck and have fun, it's a great quilt.

Your quilt is lovely, choose threads that will not distract from your pattern.

I can't help with the thread color for quilting but I don't know why you don't care for it much. I really like it.

Why have you quilted with only white thread. I would use a cream or light brown for the main portion of the quilt and brown for the sashing. Another alternative would be a variegated thread as they come in very beautiful colors and give a new dimension to quilts.

I would use gold on this or a gold green and do feathers but if I do not want to show it I would use a linen or natural color. Odd enough I never quilt with white. You did a great job on this quilt. It is very attractive and classic looking.
Here is a quilt I used the green/gold on.

it so depends on the look you want. If you want the quilting to blend into the top, use brown on sashing and triangles and an off white in the squares. If you have a pattern you want to highlight, use a brown or light brown in the white squares. You could use an off white or beige to do a scroll pattern in the sashing. I personally would not because I would prefer the focus be on those great looking blocks. I know this sounds like a lot of wishy washy advice, but the bottom line is what do you want to do? what do you want to highlight? or blend in?

another option would be to use Monopoly thread

beautiful quilt and anxious to see when finished.