I suggested playing different C modes over C progressions. When I suggested trying C modes over a C tonal center chord prgoression, I wasn't talking about playing C Locrian over a C Major progression... I'll try to clarify what I was trying to get across in my first post. First try putting the modes into three categories: Major, Minor and Diminished.

Major - Lydian, Ionian, Mixolydian
Minor - Dorian, Aeolian, Phyrgian
Dim - Locrian

If you're playing in C Major, with chords of say, C, Am, F, G, it sounds "normal" to play in C Ionian. But, you can use other C modes to get a more exotic sound that you may like better. I've found that sometimes, a minor pentatonic scale fits quite well over a major key. Try recording thsi C, Am, F, G and playing in C Minor Pentatonic. It gives the song a very blusey feel. You can also play in C Lydian or Mixolydian, but any other modes is kind of pushing it.
Playing a song in A Minor, such as Am, F, G, E, one can use the A Dorian, Aeolian, or Phyrgian mode, as well as A Harmonic minor. Don't try playing in A Ionian, though...
Now finally, that weird little locrian mode... I've only written one progression that scounds good and the locrian mode fits. Am, Bb, Am, G... try this either with power chords, or with a reggae feel in the upper register - both sound pretty cool, and A Locrian fits over it, as well as A Minor pentatonic.