A pot of tea, an afghan or two, a snuggly companion animal (cats in my case) curled up beside me, and a good book. That's my idea of paradise.
Another danger for people who sit at desks a lot is deep vein thrombosis (blood clots in the veins of the lower leg that can break loose, go into your lungs and kill you). I lost a colleague that way. Standing lessens the danger of this also. I have to have a foot pedal as I type transcripts of tapes. Because of problems with leg and ankle swelling, I figured out a way to fix my foot pedal to the wall so I could work from a recliner, which has really helped. I never thought of a standing desk. I wonder if you could use a foot pedal while standing? I'll have to try it.
I'm curious about your setup. When you decide to work sitting in your desk chair, do you shift your keyboard to the lower shelf?