One bit that has helped me use the whole neck for solos is learning scales both vertically and horizontally, vertical being the box patterns that we all know and love and horizontal being just learning the scale on each string, as well as learning all the scales starting from random places on the fretboard.
sure it takes a bit, but damn, its definitely worth it, once you get it all.
Also, depending what scales (and/or modes) you know, they may all tie in together. If you know the major scale (or the Ionian scale) then you already know 6 more of its modes, and to change modes you start the scale on a varied degree. sorry that sounds confusing...
the Dorian mode of the major scale starts on the second degree of the major scale. Let's say you were in C Major, just to make the theory bit simpler, if you were to start on the first degree, C, you'd play the Ionian or major, if you were to start on the second degree, D, you'd be playing the dorian mode, 3rd degree is phrygian, 4th degree is Lydian, 5th degree (or dominant) is the Mixolydian mode, 6th degree is Aeolian mode (which is your natural mionor scale) and the 7th degree is the locrian mode.
Anyway, all that may seem like a lot, but after playing it all out on the fretboard, it gets easier the more you practice (as with all things related to music). Anyway, hope this helped some, and good luck to ya.