What is the size of the print on your focus fabric? That would determine the block size for me.
For myself, I'm fond of Disappearing 9-patch with the focus fabric the main square and one or two coordinating fabrics for the center squares which get sliced (depending on the pattern you want to develop with the coordinating fabrics (i.e. pinwheel, lines, etc)). The pattern can be done in a variety of sizes, depending on the print.
Show us your fabric and we can help you find something that might work.