I use prisamcolor all the time.
I did a hand drawn deck of Tarot cards over twenty years ago, using markers and prismacolor. I sprayed them with krylon at the time. I have used them a lot over the years, and they have worn quite well. The edges have browned from handling, but the images are still bright and clear.
For prismacolor artwork though, I use no fixative. Places I have used the pencils heavily may "bloom" after a while, caused by changes of temperature. This is a whitish haze that rises to the surface of the drawing. I wipe it off with a soft cloth.
Otherwise, the drawings I have stored in stacks on shelves, or in portfolios seem to be doing fine. Like any other medium, you want to keep handling to a minimum. When you frame them, make sure the glass is NOT right up against the surface. Use a mat or spacers.
Do NOT shrink wrap them. If you want to simply wrap one on a firm backing, use fomeboard, (it doesn't have to acid free unless you have one for the ages, regular fomeboard is more inert than most drawing papers) and wrap in acetate. You can even get acetate bags with peel and stick flaps at
http://clearbags.com/