I would go matt stainless steel, it will match any other silver or chrome in the kitchen (cupboard handles;tap; toaster etc). I've been looking at double bowl stainless undermount sinks and thought the Blanco essential U2 model was pretty nice (and about 788mm). good luck!

If you have a stone or imitation stone benchtop, you pay a lot for that benchtop and the streamlined look, and having two sinks and a drainer cut out of that top doesn't make a lot of economic or visual sense. I have a single undermount sink with a portable drainer, which I quite like. I'd probably suggest a flushmount as a good alternative, in that it doesn't take out so much of the expensive stone. If you need a double sink with drainboard, I'd be looking at alternatives, and I was very fond of the corian-type benchtop in our last house.

I only specify an overmount sink for clients if the benchtop surface warrants one. The last time I did was because the client wanted a timber benchtop. I managed to find a beautiful black quartz composite sink that worked well and looked like a feature in the kitchen because it matched the colour of the cabinets. My usual go to sink is definitely undermount because of its aesthetic and practical advantages. Small chips can always be smoothed out if need be but really, there is no substitute for being careful!

Personally I would go with a stainless steel sink for stain removal and bleaching. Stainless steel sink is stain-resistant and easy to clean. They do not crack, chip or peel in long term use. Plus they will look good with your other two stainless steel sinks.