We got the Ticor S805. The bowl size is listed at 13" x 16-1/2" x 7-1/8", and this has worked out perfectly for us. It's big enough for anything we've wanted to prep, but it is small enough not to take up the whole island. We have been very pleased with it.

Here is a link that might be useful: Ticor S805

We originally wanted the same sink as holligator, but due to tight plumbing considerations, we had to go with the 16" round S905. Talk about a happy accident! We love it and find it very spacious for rinsing cutting boards, filling and draining our pasta pot, and thawing frozen stuff in cold water.

We've gone with a sink similar in size to the Ticor 805; we chose an Oliveri because tight island plumbing and disposal considerations required a center drain rather than a rear drain. [That's something you might want to discuss with your GC or plumber, too. The water lines and waste lines take up a lot of space in the back of the sink cabinet, as will the garbage disposal.]

We would have liked a somewhat larger prep sink, but the size was mandated by our local water management district. Nevertheless, we expect the size to be fine. It's more than twice the size of the tiny sink we've been using for prep work for 20 years, which is the smaller part of a 1-1/4 double sink.

I went with the Rohl Allia bar sink and love it. It is 17-1/2 x 17-1/2

Thanks for all the links and tips. I never thought if I would be limited to a size due to plumbing. I will have to ask contractors. The island will be 3.5 feet by 9 feet. Should I be ok?

It's the size of your island sink base that will crowd plumbing. For us, it was the standard 24" depth of the cabinet. Once they got the vent loop installed in the back of the cabinet, there wasn't enough room for a faucet to fit behind a 16" deep sink. That's why we went with the 16" round sink- the faucet could be placed in the corner where there was room.

Our bowl is similar to holligators--our sink is 13" wide and we managed to squeeze 18" (front to back) into our standard 24" cabinet, under a window (with backsplash and window ledge competing with the faucet for room.) I felt for the plumber--reaching behind our 10" deep sink into the tiny space behind it for installing the faucet...and squeezing his shoulders into the narrow door opening. It looked extremely uncomfortable.

Anyway, I love the 13"x18"x10" bowl size of our medium Blancoprecision and wouldn't want any smaller or any larger. We used the prep sink as our only sink for a while and it was large enough for anything I wanted to wash--including our largest stock pots.

I think it depends on what and how you cook.

Despite my prep sink being large by most standards -- 18" wide by 19" deep by 9" (a 7 1/2" undermount) -- my cooking would be easier with a larger one. That's because I prep several fresh vegetables at the same time and it would be easier if I had room to soak and drain more at the same time. But my kitchen is small and sink size was a trade-off with having enough counter space. YMMV.

BTW, this sink is not big enough for my cookie sheets. So measure your equipment if that's important to you.

If you want a larger sink but are supposedly limited by space, do your own research. Our cabinets were ordered back when we were still too naive to know how small a 25.5" cabinet for the cleanup sink was, so we were very unhappy at sink selection time. My DH went on-line and found a 25" x 22" (drop-in with corner hole) that Ferguson's hadn't offered us, but did sell to us. It didn't even need the neighboring cabinets to be notched (another way to get a larger sink).

My island is 4 ft x 6 ft and I have the same 21x19x10 Elkay D Bowl as my main sink. If my island were smaller, I would have gotten a smaller sink as well so I would not lose prep area. I do not feel it is too big.