Wow! I'm so impressed. I just set aside a quilt with a single set of poorly constructed borders (my own work from several years ago when I was (more) clueless)...as I just didn't have the patience! What a wonderful thing to have 'rescued' this quilt and put it together to it's best advantage. It's just beautiful, and I like the navy border, makes it look very crisp!
Don't give up. I had a little issue with waviness in the outermost border even though when I attached them I had taken all the measurements etc. The best way I could think to quilt it was to do the piano key effect. It did make for a little more work ie lots of threads to tie off and using the walking foot but it seemed to do the trick. Also had to resist the temptation to flatten out or smooth as I went along, that probably would have made a mess.