These are coming out so fun! I love the colors and the variety of choices everyone is making. If you think your quilt is too busy ADD A SOLID strip. Jaba did a medallion where she added a strip between each and every round. It broke things up nicely. I like small and large breaks (2 and 4") myself. I like your corners btw quilt addiction.
The kitty quilt is coming along so cute. Love the birch fabric also and most of these rounds can be done with as many fabrics as you want to use. You can do things a bit of this a bit of that make every other block a different pairing of colors I know my round had the option to use all scraps and if you look at mine it works. 6 different reds went into the chevron or rick rack pattern. so think outside the box and you will make your own version. As emma has shown its ok to just go for it with your centers.
The concern on one little quilt was overwhelming the center? a strip around it now would break it up, doing a checkerboard like the kitty quilt as on it is not too busy to go around and slow frame it a bit more. This is supposed to be a challenge. I know that for most of you this is the first time working on a quilt with so many borders and bordes that are not just wide strips. Think of what you will learn and how you can apply some of these borders on other projects you have that otherwise might have been bound up with a strip! your quilts will look like the ones you admire all the time in magazines and books. I am on my fourth round robin and still not tired of it.