30" for hood flanked by 12" wall cabs, leaves a 1.5" buffer between the windows.
Have you considered an undercabinet hood? Example linked below. They can be nice, still allowing wall cabs to remain a focus. Storage above is partially consumed by vent pipe.

Here is a link that might be useful: Kobe undercabinet

Thank you for the idea, seattleCraftsman. I've been reading around on GM about the advantages of doing a 36" hood with a 30" range so I think I will try to fit the 36" hood if possible. However, a 36" hood would leave me with only 9.5 inches on either side of the hood. I think that is not enough to install an undercabinet hood like the Kobe.

Yes, an upsize hood is typically going to have the advantage over a smaller one. Helps to keep anything to the side from catching spray/steam.
That said, if you want the 12" cabs, a nice 30" hood can move some serious CFM and the size cabs act to some extent as a funnel.
Do you plan to do a lot of grilling on the range?

A client of mine got this one last year. It looked great and they love it. Kinda pricey still but Zephyr offers other types too:

http://www.us-appliance.com/ak7000.html

I've also had clients that really like the Broan Allure and Evolution....a step down but not quite the low end hoods you see in stock at box stores.

Broan has a few that look the zephyr too in the $400 range I think.

http://www.us-appliance.com/rp130ss.html

seattleCraftsman, I don't do a lot of grilling on the range, but I do occasionally sear things. My biggest ventilation issue is with the long, slow cooking foods like chili or spaghetti sauce or roasts. Since I don't have a good hood, I end with a house that smells like onions for days!

kompy, thank you for that link to the Zephyr. That looks better to me than some of the other under cabinet hoods I've seen. There are some pictures on houzz where the hood was flanked by 2 cabinets but had no cabinets above it. Then all 3 pieces were topped with a filler and the same crown. I have 8' ceilings so that might work for me. I will have to investigate the recommended height for installation on the various under cabinet hoods out there.

Maybe once I see it mocked up on the architect's super-snazzy software, I can get a better idea of what it will look like. I want it to function well, but I also want the scale to look appropriate.

I bought the Zephyr Typhoon under-cabinet hood. My requirements were (1) quiet operation, (2) move lots of cfm since my kitchen, dining area, and living room are all open to each other, and (3) unobtrusive look. I could not be happier than I am.

Zephyr gives great service, too! The granite installers bashed in the front of the edge of the vent hood. Zephyr got a replacement part and a repairman out to fix it very promptly. About two years later, something went out - can't remember what. Again, they got the part to me (free) and sent a repairman to install it (not free, but that is no surprise). Every time I've called, I've gotten someone right away who has been most helpful. Not a lot of phone-trees and other falderol to go through. I am a very happy customer.

Here is a link that might be useful: Zephyr Typhoon

I have a Zephyr Tycoon under-cabinet hood also. It is quiet, works very well, is compact with great lighting and it is beautiful.

I researched on this site for months for a kitchen update and made this choice for the hood.

It moves so much air. I'm glad to hear customer service is good. Good luck on your remodel.