I'm still trying to expand my repertoire of designs, so I definitely try out new things, although I also have some standby designs that work well in various situations and I incorporate them too. I buy books from longarmers like Angela Walters, Karen McTavish, etc. and take classes when possible. I was really blown away by Judi Madsen's book, Quilting Wide-open Spaces. I also take Machine Quilting Unlimited, the magazine, and take lots of close-up pictures of good quilting when I go to quilt shows. I find quilts on the internet and save pictures in a folder for later study. When I get a quilt with a specific pattern I often look for quilting examples on the internet or in books, not that I always use those examples, but they furnish ideas. I don't do pantos, so I look at free motion designs and ruler work.
I just got a friend's quilt, and have been staring at it. Angela Walters just did a tute on making her paisley feathers, so I'm thinking about incorporating that into the design. The quilt has large pieces of a fabric with a very large floral print, really lovely, so I'm also thinking about doing some stitching to accentuate those flowers. It will probably take me at least another day to decide what to do.