Additional info from Icon Microwave installation guide: ÂCan only be installed over ranges or cooktops with 33" maximum width. It does not specify "professional" vs. "consumer" but the salesman said that because it is a professional range you cannot install the microwave over.

The only rule is that the cabinet bottom be 66" from the floor (i.e. 30" off the counter) The problem today is that many OTR microwaves are nearly 17" or taller…which leaves 13" or less of clearance! Many of my clients are pushing the cabinets to 69" or even 72" off the floor to give more clearance for the pots on the stove. That puts the bottom of the microwave around 52-55" off the floor (16-19" of clearance)

Here is a link to ajmadison website. You can look at their OTR MWs and sort for size and color. AJ Madison OTR MWs page

I'm surprised by your comment about microwaves with trim kits looking gaudy. I've never seen one that looked terrible. Many companies sell them and they go hand in hand with specific models of microwaves so that it is a custom looking fit made to fit into a standard size opening (24", 28", 30"). GE, LG, Panasonic etc - they all seem to have them. Have a look and see if you can't find one that suits your fancy. They aren't expensive ($70-$120) for most that I've looked at and give a really nice finished appearance. Another option is the microwave drawer - the most common one is made by Sharp. I think they look great and many people like them at the lower level. That way, especially as you age you aren't lifting hot items down towards you, rather up onto counter level from the drawer. They are not an inexpensive item but look and function well and can be quite hidden if you put them on the backside of an island configuration.