I prep b/w the prep sink and cooktop.
If your sink has a DW next to it, try very, very hard to not have it b/w the range and sink. It's not fun prepping over a running DW or one that's open for loading/unloading, or being opened on & off ("let me get one thing out of the DW" or "let me put one thing in the DW").
As a matter of fact, put the trash pullout b/w the sink and range...I found that I generate far more trash & recyclables while prepping and cooking than I do while cleaning up (and for a much longer period of time!)
In the majority of cases, the primary Prep Zone in a kitchen usually ends up being next to a water source and close to the range/cooktop. If there's an island with a prep sink and the prep sink is placed appropriately, prepping can take place in an island. However, if there's no water in the island, prepping usually ends up wherever there is a water source.
So, as long as you have enough space and no obstacles (like a DW), your plan for the Prep Zone is pretty good!
How much is "enough prep space"? The NKBA recommends at least 36" of clear counterspace. I can tell you from experience that 24" is definitely far too little (it was one of the major driving forces of our remodel). I have 37" plus a few more inches to the edge of the sink for around 40" of prep space and it's heaven! So, try for at least 36"...42" would be even better! One thing, don't put too much space b/w them, though, b/c you don't want it to be a hike from the range to the sink for filling/emptying pots.
Here's mine:
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Quartzite
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