Learning management systems come in all flavors and mostly you will consider selecting between Moodle, Blackboard, SkillSoft, etc. based on the features you want to implement. All of them can provide the feature set you are looking for, and the choice really comes down to the quality of implementation partner you find for each.
I will propose an alternative to these, with the caveat that our company has developed a product which fits this and this might be construed as a bit of shameless self-promotion.
For large organizations, we believe a single large LMS does not work. Each team in the company wants customized content structures, workflows and analytics. We propose using a MicroLMS system which distributes the learning processes across the firm and makes it more effective.
The implementation should allow for each team in the organization to own and operate their own MicroLMS. These teams could be based on actual team structures or pseudo structures like leadership groups, induction groups, etc. Each MicroLMS has a business owner who can configure the LMS features and settings to the specific requirements of their team. This keeps the administration and user experience light and on a all-that-is-required and only-what-is-required basis.
Each MicroLMS ideally should have an inbuilt authoring tool which allows for easy content creation by business owners using presentations that they already would likely have. Put another way, you should not require to go hunting for Captivate and Articulate experts to create SCORM packages.
The apex learning team should get a centralized control panel which allows them to view and analyze aggregated data and focus on analytics and efficiency rather than learning logistics. Of course, the central team needs to have God powers on all constituent MicroLMS, but then the expectation is these should not need to get used.
The basic thought process behind this is that in large organizations, learning needs to be owned by business owners like any other business process. In our implementations across a fair number of Fortune 500 companies, we have found the business owners prefer it this way anyways.
That’s the alternative which we propound, and my advice would be that irrespective of whether it is our product or not, consider using a MicroLMS approach for such a large audience size.