I'll go against the grain here.
I think moving is better than just standing. I'd get a treadmill desk.
Lifespan Fitness makes a treadmill that goes under a desk, and then you can use whatever desk you want.
In my configuration, I have a desk I bought from a local vendor. It has a motor that raises and lowers the desk, and I mount a VESA arm to the middle of the desk. On the right side, I have the treadmill. On the left side, I have a chair. I alternate between the two positions.
Here's a picture: https://www.dropbox.com/s/089qqvaa7j5ob77/office_setup.jpg?d...
I make use of the Pomodoro Technique while I'm working... so I'm typically walking for 25 minute cycles, then 5 minute breaks between. A long break every 4 cycles, and I sit down for all the breaks.
