Try taking a look at the caged shapes for major scales / the five pentatonic positions or maybe the modal shapes - all cover the whole fret board although you're playing basically the same notes in different positions.

You might also think about looking at 3 octave scales which will again open up the fretboard for you. Once you start using the shapes that link together, you can build your own runs across multiple shapes to get from fret 3 to 15 in half a second!

:D

Edit: Meant to also say that you can do quite alot in one position as well - with practice you should be able to make music in one box position... don't rely on covering vast areas of fretboard... either approach can sound great, or boring...