My most successful wide-angle pictures are ones where I have something both near and far. Wide angles exaggerate the perspective and apparently magnify the distance between the objects (or the object and the horizon; a strong horizon can be the far "object").
Don't be afraid to get close to the ground. Wides seem to work well when you shoot from a low perspective.
Mount a 28 and shoot an entire roll with it. Force yourself to use it. Experiment and see what you get!