I would love to see a complete overhaul of the animation palette and the graph editor. Here's what I'd love to say added:

1. Spline handles to allow for better easing-in/out, spacing, and so forth of animation.
2. Show all elements in the scene at once along the left (or right) side of the graph editor, allowing you to show or hide the individual elements and parameter dials, and have the splines all overlaying each other so you can see how the elements interact with each other over the course of the animation.
3. Ability to extend splines beyond the ends of the animation. This will allow for a spline to continue indefinitely beyond the end of the animation and before the beginning of the animation to have better movement at the beginning and end of the animation.

I don't believe I'll go any further with Poser until these features are added.