OK, I hope I am going to answer this one myself, but I want to make sure I don't overlook anything. I am creating seperate accounts for each of my client websites. Since I prefer to create my websites online, I have bought a "placeholder" domain to create new client websites under. Therefore, I create an account for the "placeholder" domain in WHM and create the website to show to my client before it goes live under their domain. If they are happy with it, I then go back into WHM and change the primary domain, username and ftp username (and the appropriate passwords for those 2) for the "placeholder" account to the client domain, a more appropriate username, etc. I should be able to continue to do this with the "placeholder" domain indefinitely I believe. The only hitch I see is that the client will have to wait for the propagation period until their new site pops up under their domain. This seems very doable but I wanted to run this by those more experienced than I.