I have 42/15 with a 10 foot ceiling, and I don't think 36 would look too tall at all. I wouldn't do upper cabionets less than 15 -- you find that once you take out the box itself, some of the things you would like to display either won't fit or barely fit and you can't raise them so that you only see them for about the top 1/2-2/3.

Your kitchen designer sounds like a person who does not see all roads leading to home meaning there are many different ways to achieve the same goal... Most semi custom cabinet companies that are limited to be more Henry Ford like in production do not offer the 12" high cabinets in each 3" width from 9" to 36" or wider. They tend to offer them for the sizes used over the appliances which use them the most. So 30, 33, and 36" would be commonly needed. Your kitchen plan normally has a lot of other widths used that are not those sizes. The companies that have the stacked cabinets pre made are generally 42" or higher. I have 5 cabinets lines I offer. 3 of the 5 do not have stacked cabinets in the book.... One of the 3 has 12" high cabinets starting 12" wide but does not have a corner cabinet less then 30" high.... They happen to offer custom cabinets on a quote by quote basis which is why I like them. But you should see my point... Your kitchen designer should have explained better the reason why they did not offer you what you were looking for. It is either they feel a 27" under a 12" with a 3" crown over that is not a good use of space or.... they do not have a company they can do it at all or for the price they are planning to present to you.... That discussion would have been much more meaning full.... I can for example use a stacked cabinet that is 42" having 2 open compartments, with Showplace and shrink it 3" if you want the molding as most would... I can also with them as was suggested above just build the door with a glass panel in the top section of it. They are # 4 out of my 5 as 5 being the highest price in general.... 18" is the general rule of thumb for recommended clearance to the countertop. 15" is considered as low as you should go and 21" is pushing the upper side of reasonability for most projects... The codes as noted above are concerned with being able to set fire to combustible wood cabinets having appliances that generate heat under them... You should be able to do what you are looking for. You just have to decide what look you like, crown or no crown, and find who can offer it to you at a price you can afford...

In my old apartment we had 9 foot ceilings and single uppers that went all the way up--the top of the doors was maybe within 4 inches of the ceiling. The cabinets must have been nearly 5 feet tall. Yes, we used a step-stool to get at the stuff on the top shelves. We kept infrequently used things up there--the electric frying pan, some nice serving dishes that tended to only come out at holidays, things like that. I remember once reading guidelines about what the maximum cabinet height should be and ours were well beyond that. But we never had any issues, even though they were ancient (not sure if they were original to the 100-year-old house, but if they were installed after the 30's I would be very surprised), and had inset doors. Modern hinges should only improve the performance.

There are plenty of semi custom cabinets available that offer a standard "stacked" wall cabinet- with one long and one short section- typical 45 and 48" total height-top opening of 12" 48 brings you to 9 1/2 ft nominal, leaving 6" for molding which is nice for a stack of molding. For instance looking at Showplace a stacked 3648 is about $215 more than a simple 3636 wall. Many brands that don't have a standard stack will "combine" cabinets - you pick the sizes(which will be available from 12-42" high in 3" increments) and they make them as a single cabinet. Costs doing it that way vary from brand to brand--from slightly more to quite a bit.