Though test shots may be the most common way that Polaroid is used in the studio, Polaroid is sometimes used for the final picture as well: Type 55 has a bit of a cult following both in and out of the studio. Type 55 is the 4x5 B&W material that gives a print and a negative. I prefer Type 54, a plain 4x5 B&W print material. A well executed 4x5 B&W Polaroid still has a special magic, especially now that many people are accustomed to looking at digital previews. It is fun as well, and there is nothing wrong with you and your client having some fun.
Best,
Helen