Thanks to all of you for your comments and suggestions. I've considered every one.
Here's what I have so far.
(And I hope I can sew straighter than I can Paint!)
Stars outlined 1/4" in with blue.
Intersecting star borders outlined in and out as one unit , 1/4 " in with invisible thread. (I tried the "quilt right through" suggestion on the upper right block, it's kind of neat, but a little confusing to look at.)
Triangle type shapes spanning blocks outlined in natural (or maybe the blue as well, as someone suggested).
I'll just have to turn the quilt a whole bunch of times, I couldn't work out an all over diagonal that follows the angles in the quilt, is fairly evenly spaced and stays within the quilt spacing required. (I ordered the Hobbs 80/20 online. The site said 4", but the package says 3.5". Maybe they're just overly cautious?) In the future I'll stick with a batt that allows larger spacing.
And for those of you who use invisible thread:
Is there any problem mixing this with regular thread in other parts of the quilt?
Is Sulky premium invisible a good one?
How do you start and stop lines of stitching? (I usually do 1/4" or less of microstitching and cut tails off at the fabric.) This stuff is pretty slick, I'm afraid it's going to come undone.
Also:
How do I keep the raw edges of the outer blue border from fraying while I do all these turns? The zigzag on my old Kenmore doesn't work, just forward and back.
Thank you all for your suggestions and comments, I really appreciate it.
And I don't hate the quilt, it's just very different from what I envisioned when I started the project.