All of this is kind of silly because the only incorrect speaking/writing is the kind that fails to convey its message sufficiently. If you write, "I want to thank my parents, Ayn Rand, and God", all is well. But if you write, "I want to thank my parents, Ayn Rand and God," you may get some raised eyebrows. But otherwise, if the reader/listener understood, then the task of communication was completed successfully. So put the question mark wherever you want, Forrest.
P.S. I know, I know. There is a "right" way to speak/write for corporate and academic situations, but that is the case simply because of the stranglehold prescriptive linguistics has had on us for so long. Hopefully, it will go away over time.
