We are also working on our kitchen layout right now. Our current plan is to put the oven in the island where it would not have a hood.

That's why I often suggest a range (w/oven) under the hood and second wall oven, if needed, elsewhere that's primarily used for things like baking where you wouldn't mind any odors coming from it. Who hates the smell of spice cake baking? (And hopefully you don't burn the brownies!)

I happen to have a two-oven range and one of my ovens is my roasting and broiling oven. I can't imainge not having it - and its exhaust products - located where they will be drawn right up, and out, through the hood.

A wall oven adjacent, but not under, the range hood will not be effectively vented by it because of how steam and hot air expands in an upward cone. It has to start out under the hood to get captured..

Apparently many people don't use use their ovens like I do. My roasting oven works, hard! And I really don't want to smell last night's broiled fish or roasted garlic - as tasty as they were - the next day.

I also think a range and a single wall oven would be quite a bit cheaper than a cooktop and two separate wall ovens. If your range is gas (with a gas oven), you could still have an electric wall oven, which would give you two different fuel source types to play a round with.

Araguato

We've got a range and a separate wall oven about 5' away, like liriodendron describes. Now, if I actually used it as she describes, it would be a perfect system for us, for all the reasons she states. As it is though, I often do high heat roasting in the wall oven. Even though it is between the makeup air intake and the hood, most of the grease and steam go straight up anyway. I've really got to stop doing that. (The range oven doesn't roast as evenly, and takes forever to preheat because of its size, that's why I favor the wall oven.)