It seems like your site will be dealing with multiple functions. While WP is gaining ground as a CMS I would still vote for Drupal in your case. It is a lot more robust as far as adding multiple advanced features such as mailing lists, blogs, image/video galleries, user management and overall customization of all aspects of it. While it is true that you can add many features to WP with plug-ins, Drupal comes with a lot of the functionality out of box.
I think your main concern should be with your own experience. First it is always a good idea to go with what you know. If you have used WP it would be better to take what you have and build on it if you want your content out there as soon as possible. Drupal can take you a bit to get over the learning curve but they are making improvements for navigating around the features. Drupal and WP both have excellent communities as far as modules being developed for additional functionality but Drupal has been in the field of all-in-one community-driven software a lot longer.
To make a long post short Drupal can let you have multiple users, create and assign various roles to who can post what, who can view what, and who can do what from the start. You can add more functionality for ecommerce with something like the ubercart set of modules that would allow you to handle subscriptions. Since its totally integrated with Drupal you can automate giving access or denying access based on their roles and it can handle a wide array of payment processors. WP can accomplish this as well but it would take a lot more time and effort to tweak it.