It helps if you think of wide angle lenses as exaggerated perspective lenses.

I usually don't use them just to get everything in the photograph. You can often do that by just moving back with your standard lens.

Instead, use them to permit getting closer, while still getting the whole scene in.

Wherever possible, I try to use a lens for the purpose of choosing perspective (which is determined by camera to subject distance), rather than field of view.

Take a look at the "colour in winter" photograph in my APUG gallery for an example - that was shot on 35mm using a 24mm lens because it permitted me to get close to the bridge, and emphasize its depth.

Hope this helps.

Matt