D'karr
Adventurer
From her backstory Queen Ileosa seems to have so much potential as a great tragic villain, up there with Darth Vader or Strahd, but the authors seem to have gone out of their way to make her as two-dimensional as possible and sap all the dramatic weight from the saga. James Jacobs' posts on the Paizo boards make clear he doesn't want the players empathising with her in any way - but why not? I want to do something about that.
I'm currently converting the original A1-A4 Slave Lords adventures for my campaign. The original modules were very sparse on "story". The background for the modules gave you an idea of the basic flow of what was intended, and that was about it. Everything else was open to the DM to do as he will. These adventures are classic dungeon crawls. NPCs don't have names, they're just merchant in room 37. The intended flow is go to this location, and clear it out. Go to that location, and do the same. That type of play can get repetitive, and boring without some underlying motivation. That was something I had to inject into the adventures.
Since this is being played as part of a long term campaign, I went through the trouble of tying the PCs and their backstories to the NPCs that were enslaved, or to the people that hired them to finally put an end to the Slave Lords. The interesting part that flowed out of this is that one of the Slave Lords, Markessa, is going to become that great tragic villain. I'm working out the details but I'm pretty sure she will become a great source of friction, a thorn on their side if you will, but they will probably not want to outright kill her. I already have the hooks in place to one of the PCs and the "story" has been taking a very interesting turn.
I like these classic adventure modules because they are really just a framework that you can build upon. I tend to work well within that open structure.
I've found APs a bit more narrow and "restrictive". However, I've found that their best use is to mine them for ideas, plot points, villains and resources. If you use them in this fashion you can tailor them in extremely interesting ways. Tragic villains are great resources, and the APs do go to a lot of trouble to give you ready made NPCs with somewhat compelling backstories. I might not use as-is, but they present a good starting point for tailoring. I like it when the players end up hating, and at the same time pitying the villain. It makes their PC interactions with the villain much more satisfying.