I went fishing around for examples of "I Spy" quilts. There don't seem to be any rules. I saw some that were just square after square of fussy-cut noveltie fabrics. (confusing to the eye and not attractive - at least to me.) I think any pattern that pleases you and frames the fussy-cuts so they truly stand out would be just fine.
here are some free instructions to create hexagons within 6-pointed stars
http://www.hgtv.com/hgtv/cr_quilting_other/article/0,1789,HGTV_3305_1394148,00.html
if you like the idea but find these instructions too complicated, let me know. i'll make you some simple instructions - and templates - if you'd like.
you could just as easily make snowballs, squares in squares, attic windows, friendship stars, or ..... well you get the point.
there are dozens of sites on the internet from which you can get ideas and free patterns. The Quilters' Cache is one of my favorites ... beautiful illustrations and detailed instructions.
http://www.quilterscache.com/QuiltBlocksGalore.html
just have fun with it and make sure to show us a phot when you're done. :-)