I wish I had the vision to help you but I don't. I like what you did on the first quilt. Matching the background is a good start. Friendship stars or Flying Geese might be good fillers. There are quite a few spaceship patterns. I searched for Spaceship Quilt Pattern in BING and found lots of good ideas.
Another idea might be to make these blocks the center of log cabin blocks with Fg as the sashing.