I don't think a sitting desk would be a good choice unless you elevate it or happen to be short in physical stature. You will want to set your table height to a comfortable working level, so when you bend to focus or make some adjustment at your work area, your back is not over-taxed. You also donít want your work surface too high. Next to your enlarger choice, good bench and tray/sink heights can be the most important darkroom decisions you make.
A good way to find out where to start is to stand upright with your arms at your side with your 'good' hand flat, level and palm down. Whatever measurement you get from the heel of the hand to the floor would be the minimal working surface height. This method is what I used to determine the surface height for several workbenches and I have found it to work pretty well. I donít think youíll want to add more than an inch/inch-and-a-half to this measurement. You also want to keep any floor mat height in mind when tweaking your worktable.