If stacking is the only option, I would definely put the steam oven below the microwave. How tall is the person who will use the ovens the most? At 5'8" I'd put the steam oven at around 34-36" above the finished floor height and the microwave above. I'd figure out what the plan is for cabinetry and make the final determination based on how it all works together - If I had cabinetry on either side of the stack, I would move the stack a few inches up/down based on whether that meant doors or drawers surrounding the stack would line up horizontally.

I'm 5'8" so that works for me. I was just measuring the spot and put tape up to see how it would feel. I put the CSO bottom 33" from the floor. But if I could put it up to 36" without the micro being too high, I would like that better. Time to measure again. Many thanks!

I would try to get the MW no higher than your shoulders and work from there.

Do you have landing space directly adjacent to the oven cabinet in which the MW and CSO will be installed? If not, consider adding a pullout shelf b/w the MW and CSO for landing space for the MW.

Not sure how the shelf would work with the CSO since it would be above the oven. However, the NKBA does say that landing area above an oven is acceptable, so it may very well work for the CSO as well.

Ideally, you should have landing space nearby for both...

NKBA Recommendations:

That's good info, thank you! I won't have a landing zone next to the ovens. I will have to remove the dish and turn around to the landing zone.

Now I'm thinking about placing the top of the Miele microwave at 70 inches, it's 24w x 18 ht. and then putting the Miele combi-steam oven below it. My goal is to get the CSO as high as possible.