The larger is better if you do lots of dishes with multiple pots and pans on the cooktop at once. It will need to have a larger cabinet to house it, plus a larger and more powerful vent above it. Be sure that you are planning at least a 42" vent hood, and that the run of counter space to either side of the cooktop won't be too small if you switch to the 36" instead of a 30". Many smaller kitchens can't afford to sacrifice that extra 6" of space.

I would recommend a 36" cooktop 100% over a 30" cooktop. The reason is that in a 30" size, the knobs on the cooktop will take up valuable cooking space. Please visit an appliance store and check out any brand's 30" cooktop, and you will see what I mean about the knobs on a 30" cooktop. There is very little room left for a larger fry pan or pot when you lose those inches from a 30" cooktop to make room for the knobs.

I do not entirely agree that a 36" cooktop requires a 42" vent hood. It's a nice-to-have, but you will be fine with a 36" hood. Just make sure the hood is deep enough to exhaust the front burners (i.e. don't get a hood that is shallow from front to back, even if it's a bargain).

Another alternative if you do not want to lose valuable countertop space to a 36" cooktop, is a 30" "rangetop". A rangetop is basically the top part of a range, without the oven underneath. That means the knobs are across the front, like a range, rather than taking up valuable cooktop space. Another advantage to a rangetop is that it will be easy to switch out to another rangetop in the future if need be, cause there is no countertop cutout. A cooktop on the other hand, has a countertop cutout specific to that particular cooktop. Should you need to switch out the cooktop some years from now, it will be very difficult to find a cooktop with that exact cutout to fit. We have seen that situation several times on this forum.

And, many people prefer the more "professional kitchen" look of a rangetop, but that is individual taste. The disadvantage to a rangetop is that it is more expensive than a cooktop.

Here is a link that might be useful: Kitchenaid 30-inch Rangetop (Looks like there are rebates available from KA right now!)

This post was edited by alwaysfixin on Sun, Dec 16, 12 at 12:32

Thank you for your help! I did not think about knob placement, alwaysfixin. I currently have a range, so it will different moving to a top, and seperate ovens.

It is a new construction home, and the hood is 36", and the base cabinet is also 36". It is a large kitchen and can handle the larger top.

Drewem - you will find it so easy moving to a top and separate ovens! I had to do the reverse, and move from cooktop/separate ovens to range. Much harder! If you get the rangetop, rather than the cooktop, it will be even easier for you. In any case, you will love not having to bend for the ovens (even though you might think this is minor, once you have wall ovens, you'll never want to bend down and peer into a range oven again). You will also love the flexibility of two ovens. And you will love not having to stand in front of a hot oven while working at the stovetop. Good luck, and let us know what you end up with.

P.S. Whether 30" or 36", I still think the ability of a rangetop to be easily switched out in the future if need be (appliances these days aren't made they way they used to), outweighs the additional upfront cost over a cooktop. If you are not planning on staying long in this home, it doesn't matter I guess. But if you are staying a number of years, what will you do if your cooktop goes kaput and you need to replace it, and can't find one to fit your cooktop's countertop cutout? Just my $.02.

This post was edited by alwaysfixin on Tue, Dec 18, 12 at 8:31