quiltsRfun - - -
IMHO - - - you might want to consider a 'constant' that gives you a bit more contrast; makes all your other colors pop as mentioned by others posts. To my eye, the 'constants' you're considering blend in too much with your beige/light brown FQ's. Try a red or a yellow! I agree with the idea of making up a mock-up block - any pattern - so you can 'audition' your fabric choices. I'm sure you'll come up with something great!
I've changed my mind probably half a dozen times before I finally decided on my color choices so I know it can be a challenge.
Jane