You know it's what your cat's thinking.
8"x10" and 11"x14" I print on my own professional printer using heavyweight matte paper and archival pigment-based inks. Which basically means that it's a high quality print that'll last a long time. I ship them flat in bend-free mailers.
16"x20" prints I get made on lovely satin-finished poster paper at my friendly local print shop (super local, they're an 8 minute walk from my front door) and ship them to you rolled in a tube.