You don't need to put the bottom in if you don't like it. You could leave it out entirely, or use a stiff interfacing like timtex, peltex or stiffy from Long Creek Mills. these will give support, but won't be stiff.
here are my favorite sites for free bag patterns. Maybe you can find something here
http://pursepatterns.com/free_bag_patterns.html
http://www.allpeoplequilt.com/projec...terns_ss1.html
http://www.allcrafts.net/sewing/pursesew.htm