It's a standard 18'' no matter how high the ceilings are. That has no bearing on the distance between base and uppers.

The normal space is 18" for the backsplash between lower and upper kitchen cabinets. Within this space, you can choose to use the 4.5" h backsplash in the same material your counter is in. It can be very dramatic to use the entire 18" to create a design statement using decorative tile inlay for the entire backsplash. With you 9 1/2 foot height of ceiling, you certainly have the ability to instal the taller upper cabinets, but the backslash distance stays the same! Enjoy your remodel!

Thank you for your help...now that issue is resolved, Very Grateful