Yeah, I'd never use a glue gun for scrapping, but I use just a WM gun for other crafts. It's been my experience that all glue sticks are stringy and you just have to put up with it. But my scrappy adhesive gun of choice is my trusty ATG 714!
I second the recommendation of Glue Dots or Zip Dry to adhere the buttons to the flowers. Every glue gun stick I've ever tried is not only stringy, but it comes unglued too easily, too. The glue dots and zip dry glue don't have those problems.