I have a similar setup and love it. The rMBP 15 sits on the large pull out keyboard tray and the LG monitor on the desk above. No need for books or such. The rMBP and LG screen meet at the perfect point. The keyboard shelf is wide enough to lay reference papers beside the laptop, a very comfortable arrangement.
I use the rMBP screen for text the larger LG for video and photo editing. No extra boxes around to clutter up the work space. When I want to go mobile, pull the TB cable and go.
I used to use external keyboards and mice with previous MBPs, but they were so constraining.... but the MBP was not all that portable to begin with I guess. And the newer rMBP keyboard trackpad with gestures is so sweet to use, and light enough to be portable with no fuss.
There are many old school folks about that use what they like. Nothing wrong with that.