I settled on pastel hearts, made using freezer paper and holding the turned edge with glue stick. Next step: To figure out how to do machine applique. I've been doing hand applique since I was a kid, but doing it by machine is a little scary. Looked at a number of tutorials, but learn better by doing - so I consulted my sewing machine manual, grabbed a bold colored thread, and give it a whirl.
Yikes...maybe I should take a class. These hearts are going to be hand stitched! :)