Simili paper is made from wood and cloth pulp and is a lower quality than art paper. Simili usually has a yellow tone, a coarser texture and is a little lighter weight than art paper. It will be very similar to that used in a paperback book, only heavier. Art paper is a high-quality, white paper usually coated to allow better ink adherence and to provide a better surface finish. Art paper is heavier than simili, but not much. Personally, I would go with a slightly heavier paper for a brochure. I would also suggest consulting with a printing company such as Alphagraphics. They will usually answer questions like that, especially if they think you will be buying something from them. Hope this helps.