Thank you for your suggestions, everyone. I'm really curious about the Michael Miller Cotton Couture line. I've found some online, may have to order a small amount to get a real feel of it.
I'm also tempted to just go with the "good" Kona I have that was bought at MSQC (not the ones from JoAnn), and use Best Press as needed.
I'm just itchin' to get sewing this thing! Design and planning has been too long of a process for me, although necessary to get it right. My son is an adult, and plans to display the quilt rather than use it. I know, sigh...