I would love it if we could interact with the different slaves. (Completely understand what I'm going to suggest would be a lot of work).
Being able to talk to the slaves would add a lot of immersion, and there could be a system for "breaking" them/making them loyal. Different slaves could have different kinks and personalities, so for example, the whipping station could be very effective at making one slave submissive to you, but another might hate it and try to escape if you use it on them too much, but instead responds very well to being pleasured. You could have jobs around the base that you assign them, and then depending on their performance, you can punish or reward them, and what a punishment or reward is would depend on their kinks and preferences.
I would also love to be able to dress up the submissives!