Don't take this the wrong way, but, there is that but word; you are trying to make this way too complicated. The I, IV, and V7 chords of a key have been used to write a zillion songs. You can do a lot with just those three little chords.
The I chord is the tonic or tonal center of that scale/key. Brings rest and resolution.
The IV chord is the sub dominant which wants to move to the dominant V7 chord, and the V7 wants to move to the I tonic. If we use that progression we move from rest (I) to tension (IV), tension is good, to climax (V7) and then resolve back to rest when we return to the I tonic chord. We brought up a thought, discussed it reached a climax and then brought that thought to a conclusion. Do the same with verse number two. Verse number three and the chorus would be well served with that same progression.
Those three little chords have given you the classic movement a verse needs, to be interesting.
So....... Start there. If you want color and flavor the ii can sub for the IV. The vii can sub for the V or V7, that leaves the iii and vi for color and flavor. This need not be complicated.
http://tabs.ultimate-guitar.com/m/mi...banner_crd.htm
Now for the melody use the notes from the chord's pentatonic scale. While the I tonic is active in the song use it's pentatonic notes for your melody. When the next chord is active use it's pentatonic notes. No not in scale order, make a melodic phrase out of the notes, i.e. whole steps, half steps and leaps and don't forget to leave pauses. We like to hear four note phrases with pauses.
OK how many like notes per measure? One gets harmonization, two like notes will be better, three are probably not necessary. Each chord's pentatonic will give you three like notes for harmonization and two safe passing notes for color and flavor. Help yourself to what you need.
Have fun.