There are a couple of materials i would recommend for doing wall graphics...
GMI wall graphic material (4 and 6 mil available) vinyl wall graphic material, solvent printable, excellent color, easy to work with, requires a bleed to prevent curling on wall
Seramark - fabric based solvent printable material, excellent color, phthalate free, CPSIA compliant, no bleed required
These two materials are the most consistent performing materials i have used for this type off application. We have tried others, while the print was nice, it was tough to prevent it from curling once applied to the wall.
Samples available on request