I have purchased the Session Drummer expansion packs and although they are ok, I would recommend going for something like Steven Slate Drums, Superior Drummer, or BFD. You can get them for a good price on eBay especially if you find a dealer where you can make an offer. I'm in the process of changing a projects MIDI performed rock drums to use Steven Slate Drums (SSD4) and it's making a huge difference. Having the snare bottom, overhead, and room mic's for me is what takes it to the next level and allows for a more "organic" sound.