Hello Kircan: Thanks for your question, it is very important when designing worksurface.
When you're seated or standing in the position you'd use the desk, rest your arms at your sides, keeping your elbow at a 90 degree angle and your upper arms in line with your torso. If the desk is the right height, your hands should rest comfortable on the desk. So if you will have it custom, go through this exercise with the builder. You can also choose an adjustable chair that yo can control the height of the seat and the arms.
Hope this helps, Good luck.

Hello, Will you please tell me the distance between the desk surface and the cabinet above it?