Brandon............
I use a lot of walnut in my risers as accents, beautiful wood and also use walnut for lams, makes a fast bow. I like walnut incombination with IPE for strenth. I have used cedar in a few risers and it works good as an accent as you suggested. I would use more if I had a good supply. I would be afraid to use either one without some lams to strenthen the riser.
James...................