You should go to the Appliances Forum where there are extensive discussions on hoods (I'll link below).

- Ideally, your hood should be 54" wide, so that there is 3" of capture area on each side of your range. But if your hood is 48" wide (due to cabinetry or space limitations) that's OK.

- Your hood should be no less than 24" deep, and many people feel that 27" deep is better (personal choice there). Don't worry about hitting your head; you will get used to the hood being there and won't hit your head.

- to calculate the proper amount of cfm's, add up the btu's of your range, divide by 100. For example, if you had a 30" range, with 15,000 btu's on each of the 4 burners = 60,000 total btu's. You would need a 600 cfm hood. Many people might say it's overkill because you won't have all burners going at the same time. Well, that's up to you, but at least you have ballpark cfm's to aim for. However, be aware that it is better to run your hood on a lower setting most of the time, than have to have it cranked to full power (because you undersized on the cfm's). That way it will be less noisy, and still have the power to crank it up on those occasions you need it when frying steak or stir-frying or whatever.

- baffle filters are better than mesh filters, because mesh quickly become clogged with grease and need to be cleaned more often or will be rendered ineffective.

- do not skimp on the ductwork! It should be at least 8" diameter, and perhaps 10" diameter depending on which hood you have. Anything smaller than 8" will give you much greater noise, and diminished efficiency. Don't listen to your GC if he says 6" is OK--they often say that because 6" diameter duct is easier to install. Stand firm. Also, the more bends you have in your ductwork, and the longer the run to the outside, the more noise and the less efficiency. Try to keep bends and duct run distance to a minimum.

- if you are building a new house, it is likely going to be well-insulated and tight. With a powerful hood, that might mean you will need make-up air (aka "MUA"). In some locales, MUA is required by Code. There are a lot of discussions of make-up air on the Appliances Forum.

- There are a vast number of hoods on the market, and you have not provided a price point for us. If you have a sizable budget, Modern-Aire is very popular on this forum, and they are very beautiful. Slightly less money (though still expensive) is Independent Hoods which used to make the hoods for Wolf until Wolf decided to make its own hoods in-house. Kobe hoods are more budget-friendly, and still very good quality. If you want to be matchy, you could get a Viking hood, but I don't know anything about their hoods. Viking doesn't have that great a reputation for reliability, though I think they are trying to change that perception.

Here is a link that might be useful: Gardenweb's Appliances Forum

akchicago named some good brands, and there are others as well, suchas Prestige.

You can buy a hood with the blower inside or you can buy just the blower unit and have it installed in a custom hood.

I have a Prestige in a custom hood. 1200 CFM. It works very well but it is loud even on low. My friend has a Kobe and CFM for CFM it does not seem to be as loud.

Read everything and try to check out your choice in person before you buy.

thanks for the advice - the cfm and the distance issues have been the subject of a lot of discussion on this forum; but, no real definitive advice - i'm going with the 48 in range and the 48 in hood - 6 burners + the griddle - i'm going with 1200 cfm - i'm suddenly under some pressure due to the lead time of the viking range with cobalt blue front

Take a look at the Vent-a-Hoods with the "Magic Lung". It is SUPER quiet and there are no filters! I have one and I LOVE it.