What are some of your favorite plugins? The only one I have much experience with so far is FXPansion Geist sampling drum machine. It's pretty amazing. One stand out feature for me is that it can automatically slice a sample into parts and then analyze those slices based on their frequency content and classify them roughly as bass, drums and high hat. Then it will distribute and layer those newly created instruments into your pads with a single click. You can very easily make very interesting sounding drums from samples of pretty much anything using this feature!
I'm a sucker for CPU intensive things, so I'm going to try U-he-diva today. But man are VST expensive! So with that in mind, does anyone have any experience with http://www.vst4free.com/ There's some pretty intriguing looking stuff out there for free to be sure

Moving into this space, and wanting all the most intense VSTs is making me really wish that 64 bit buzz were more complete!