If I play a G maj  C maj D maj progresson do I want to play a G maj scale? will any thing else fit ?

...if you care to "wade" through the verbage, try looking at the "Introduction to Music Theory 101" postings, specifically the sections discussing "how" the Greek "scales" and "harmonized" scale chords from the Signature (root) Key are created from the Degree (Roman Numeral numbers) notes of the Signature Key, which for the Key of G would be:

       G = ( I ) = Ionian
    Am = ( II ) = Dorian
    Bm = ( III) = Phrygian
       C = ( IV) = Lydian
       D = ( V ) = Mixolydian
    Em = ( VI ) = Aeolian
F#dim = (VII) = Locrian

...for your example, an Ionian scale would fit over the G chord, a Lydian over the C chord, and a Mixolydian scale would fit over the D chord.

thank u tele man