the height of each stand will vary depending on the heights of your individual kettles ,tun and stations. My brew stand is gravity and on caster wheels. Start with the floor and the height of your carboy/fermenter. raise the bottom of the previous level 2 inches above the top of that to allow room for lids or plumbing fixtures. Boil kettle then Mash tun levels , same way above the next station and up the line until you reach your strike water kettles heat element. So, my brew stand has 3 levels , my carboy sits on the floor and I move it with a 2 wheeled dolly cart to its fermenting place.
If you go with a pumped system ,you can surely make your brew rig one level .