Ok a few things to make sure i got this shit right...
If i play a song in say G (major) then the solo can be any of the following:
G - Ionian
A - Dorian
B - Phrygian
C - Lydian
D - Mixolydian
E - Aeolian
F# - Locrian
(Not including Harmonic/Melodic minor here) And all are constructed from the same note, you just start from a different one depending on what type of sound your going for.
Correct?
that is correct if you want to play in G major/E minor. However you can use whatever scale or non tonal doodle you want over the G major chord. Although it is the 'guidline' that whatever solo idea you are playing gravitates towards the notes of a g major chord, but you can solo in F# melodic minor if you wish over that and if you think it fits, however it is not guaranteed to please many people

Over a G major the following scales would sound good too, and more interesting than the standard g major. G mixolydian (aka A minor) for example will sound amazing on top of that. It contains the same notes as the chord:
G A
B C
D E F. THe bolded notes are the ones contained by a G major chord in any voicing. Another example is G lydian:
G A
B C#
D E F# G This will give you a nice twist to the melody over it.
If you really want to spice it up, you can use G phrygian domminant, fifth mode of C harmonic minor over the G major chord. this will yeld a Spanish effect. Take a look at the notes of this scales and that of the G maj chord:
G Ab
B C
D Eb F
Another example of a scale that contains the notes as Gmaj chord, is the 4th mode of the melodic minor. I forgot its text name, but it sounds pretty much AMAZING.
You can also use the chromatic and the whole tone scale if you focus on the root, fifth, and third of the G maj chord when you are using them.
If you want this thing to make much more sense, i really recommend Steve's online lessons, theory started making much more sense after taking lessons from the man!
(the lessons will also convert you into a Smyth-minion, who does the whoring for the lessons on boards for Steve


)-as you can see I'm a bit dislexic too...