To have "plenty room for eating on the other side", I recommend a minimum of:

..1.5" counter overhang
+ 24" deep sink base
+ 1" decorative door on the back of the island
+ 18" seating overhang
44.5" deep

Yes, you could go with a 15" overhang, but if you want room for a plate, glass, etc., and not have water splashing in your face while eating, go with at least an 18" seating overhang.

But....is this going to be your only eating area? If so, I would probably increase the depth by another 3" and consider a bi-level island with the seating area at table-height. Normally, I recommend single-level islands (and peninsulas), but if this is the sole "table space", then I think a bi-level may work better for you. With the Cleanup Zone in the island, you won't have a nice expanse of workspace, so you're not losing the biggest (to me) advantage of an island.

If this is your only eating area, do you really want to eat all your meals staring down at dirty dishes? Another reason to consider lowering the seating side to table-height!

Thank Buehl...Right now we have a peninsula that is 42' wide, flat, no sink (we may be moving so this would be for a new kitchen). Looking at what I have now, I can't imagine putting a sizable sink in there and not feel like I was sitting on top of the sink. Would 2 1/2 inches make that much difference?

Well...if it were me, I'd probably want at least 24" b/w the sink and the seating edge...I was just giving you a "minimum" to work with! (I sometimes get blasted here for recommending what I would do in similar situations, especially when discussing seating overhangs and aisle widths!)

If you have plenty of space, you could do 12" deep cabinets back to back with your 24" ones, then do an overhang in front of the 12" cabs. They would be harder to access, but could be great for storing things you use only occasionally. This way your base is 36" thick, giving a more solid look and additional storage.

If it were me and I planned on eating all or most of my meals at the island, I'd probably design something like this...but with a more consistent curve. I couldn't draw the curve in PowerPoint!

Plenty of space for both legs/knees (overhang) and body (linear space). In a pinch, you could add another seat on the curve.

If you did a bi-level island with the seating 30" high (table-height), I'd eliminate the 12" deep cabinets but keep the overall island depth the same. (I think it would be too difficult to access cabinets under a 30" counter.)

BTW...the above gives you plenty of workspace on the island for prepping and cleaning up (in case you're trying to combine your Prep & Cleanup Zones into one on the island). If it's all one height, it also gives you a relatively large expanse of counter space on the seating side for projects. Not quite as much as if you didn't have your Cleanup Zone on the island, but still pretty nice! 22" + 1" 12" = 35" deep x approx 120" wide.

You could go 45" to 51" wide. One way would be to use 30" base cabinets with a 15" to 18" wide overhang. Another would be 24" of cabinets and a 24" overhang supported by legs and a frame. (I think that 24" is too much to support cantilevered off a 24" base.) Or you could do a 12" to 15" overhang with a 36" base made of a 24" row and a 12" row of cabinets. The 12" row of cabinets either has doors on the sides or the back (under the overhang).

We used the last method above. We have our rangetop and prep sink in the island, but our prep sink is the same depth (front to back) as many main sinks so perhaps it can still help you visualize. Our island base is 36" by 96". The back row of cabinets has a 12" wide cabinet facing each side. Between those are two 24" wide 12" deep cabinets with doors under the overhang. Our overhang is 15". We were going to do 12" but we had the room and a big enough slab so we decided to go with 15" to have a bit more generous legroom.

By the way, what are you planning on using for the counter? If it is granite, you can generally get slabs of 10' by 5', which is what the larger island Buehl drew would need, but it might limit your choice. Keeping to 8 or 9' wide might give you a bigger choice of stones.

I'm short and would find the center of anything larger than our 51" difficult to reach.

We often use the 27" back of our island for kneading, forming loaves, filling cookie trays, cooling area for baked goods, etc. Also it is a nice width for setting up a buffet. Our grandchildren often snack, play or color there while we are cooking. But if more than one or two people are eating, we generally sit at our table. We could fit 4 stools, but it would be kind of strange to sit in a line to eat. If it is going to be used for family meals, it would be nice to be able to sit on at least two sides.