In my band we have some chord progressions that I am trying to create some lead and solo parts to them and I'm not sure what scales to play.

One progression is C, Em, Am, Em with a capo on the third fret.
and another one is D, G, Cadd9 for the intro and verses and C, D, G and Em for the chorus.

I want to try and come up with some lead parts and solos but I am sure what the correct scales to use for them. Can someone help me out or point me in the right direction to the info?

Thanks

Nick