Any color sashing or binding would be appropriate and effective. Some more modern colors might be lime green, orange, bright mustard, or even a warm brown.

Jan in VA

How about a very thin border of the Kona cotton color of the year? Called Highlight, a very bright yellow. Then a border of the fabrics you've already used. Very pretty btw, whatever you do it'll look great.

I would add some black sashing. I think if you added another color at this point it would detract and that's all you would see. I like what you've done.

I love to do samplers and with the bigger sizes blocks, I like to separate them with sashing. I would use a batik for the sashing - multi-colored and I would use your favorite color in the batik for a border. I would then have enough of the batik to use as your binding. Sorry, but I don't like black, white, grey together with red. I would use a grey for the backing. Good luck. It will be pretty when it is done, I am sure. Edie

I like it as it is; beautiful and bi-color quilts are beautiful.
every time I try to improve on a quilt in some way I am always sorry and wish I had left it alone.
Love it!
Mariah

For sashing, since your blocks are different sizes, do you plan to sash each block, or just the main size and put some of the smaller ones together. It is a beautiful quilt. I really do like it.

Great job! I don't know if I would add color, but it really did turn out very outstanding as is!

I'm a fan of red with black but a pop of lime green could be fun too.

One of the prettiest quilts I saw was when I took a class for tumbling blocks. A woman made the quilt for her son in black, white and gray. I thought it would be boring but it was the most fantastic quilt when she finished. I would use a black border and stick with the blocks you have.

I agree...a pop of red would be really nice