Similar situation here. LR and PS CS integrate amazingly well. I have some plug-ins in PS that I love using regularly (like Viveza), so I tend to do much more of my post-processing in PS, but I still do minor corrections like noise reduction (unless it's really bad and needs Nik's Define), colour balance, exposure, and vibrance in LR, then go to PS and finish things up. Though for many photos Lightroom is plenty to get a decent result.
On that note, I think I'd go crazy (well, more than I already am) without LRs keywords and organizational abilities. There's no better way to organize all those photos, especially if you shoot hundreds (or even over a thousand, and especially thousands) of photos a day, then using a program built for it like Lightroom or Aperture. Note I mention Aperture; they both do much of the same thing, and have their own strengths. If you're on a mac, you might as well look at Aperture too as a choice.