Ok so the first thing I did on day 2 with the stand up desk was rebuild it. At my seated desk I have always had my monitor off to one side. I now realize that I also always sit at my desk at an angle so I am actually looking straight at the monitor and thus avoid neck strain.
Yesterday I found I was standing at my desk at an angle in order to look directly at the monitor. This actually worked pretty well and wouldn't be a problem other than when I introduce a treadmill to the set up standing at an angle will become difficult if not downright dangerous. So I have moved a few things around to get the monitor in front of me. I have also introduced a set of drawers for storage at a height they are easily usable while standing.
The introduction of the draws has also meant I can now move my laptop back into view. For my standard set up I place my work onto the 30" monitor and use the laptop screen for email, Twitter, Basecamp etc.
For my second day at the desk I have stood for about 7.5 hours. My legs ache a little and I find I am most comfortable if I keep moving my legs. This is a good sign that potentially using a treadmill may actually be more comfortable then just standing.