Back when my Logitech headset broke, I was looking for a new headset. As previously mentioned in this thread, I eventually figured it was a much better idea to get a separate mic with a high quality set of headphones. I still haven't gotten a proper clip-on mic (I use the one on my old Logitech headset, little awkward but it works for now), but the headphones are amazing.
I'd planned on getting the Grado SR80's, but the place I went to didn't have them. They did however have a set of SR125's, as well as a demo set. I was sold on them immediately.
There was also a demo set of RS1's but I purposely avoided trying them. The basic rule of thumb is know how much you want to spend and don't listen to anything outside that price range. My father, however, was not planning on buying anything and listened to both the SR125's and RS1's. He's much more of an audiophile than me, but his hearing is rather poor these days. That said, he was still very impressed and noted the slight improvement in the RS1's.