For flow in your kitchen I'd put them at the main sink. It's closer to the glasses (for instant cold) and coffee cups (for instant hot) and more convenient to the snacking area, and plus I wouldn't want to encourage that traffic into my prep aisle.

I'd put it where you use it, which I assume would be prep sink. Is that where you'll make tea, instant oatmeal, jumpstart a pot of pasta water?

We might end up putting one by the cleanup sink too, since that's adjacent to DH's coffee/tea station and he likes to preheat mugs, coffee carafe and tea pot with hot water.

Ditto Taggie. I don't want interlopers who just want a glass of water or hot water for tea in my prep area while I'm working. They need to stay out of my way. I put the filtered water at my cleanup sink for that very reason.

Thanks, all! We have one going in the wet bar too so I can send the interlopers down there but thinking about where the glasses/mugs are is a good point. Thanks, GW gurus!

We're putting ours at the "extra" sink, which is actually the bar/beverage/coffee/morning food/snacks/garden/helper-prep sink near the fridge. It's closest to the dining room, hall and back door than to the range. We'll store all glassware above the bar sink, not the clean-up sink. The range is nearer the clean-up sink, and I don't want anyone walking in the cook/clean area when doing dishes or cooking, so we're keeping all other activities at the perimeter.