My day job is a draftsperson. I sit on a stool with a backrest that I bought at Costco for $100 shipped to my door, and I have two 23" monitors on an Ikea Jerker desk (think they stopped making this model) with an elevation of the desk set to about belly button height when standing.
For many simple tasks I stand and do them.. And I usually stand to keep awake if I get drowsy.
I recall reading a european study saying that standing parts of the day can add 30 minutes productivity to your work each day.