Thanks to everyone who gave me advice/opinions on Bob San. I did end up choosing to go there over Mirai, as I have been to Marai several times, but this was my first visit to Bob San. I had a fairly small dinner, but I was rather pleased with the quality of the food.
My companion and I asked the server what she suggested for the evening, a habit I think is pretty key at sushi restaurants. To my delight, they had O-toro in, and she mentioned that the sea urchin was particularly fresh and high quality that night. She gave us a standard "it's an aquired taste" caveat, but I love the stuff. We started off with several pieces of O-Toro, sea urchin, mackrel (one of my tests for any sushi joint), yellowtail, and salmon. Nothing too fancy. The O-toro was superb, I cannot recommend it enough if they have it. The sea urchin, as promised, was spectacular. Its texture had that slight firmness, just a hint, as you bite into it, and then dissolved in your mouth with a delicate seawater aftertaste. The salmon and yellowtail were both excellent as well- supple, beautiful lines of fat in the salmon, and the yellowtail melted in your mouth. I tend to use mackrel as a quality barometer- it's a fish that can get overly fishy and oily and doesn't stay well- the flesh falls apart pretty quickly after cutting. Fortunately, the mackerl at Bob San was fresh, lightly oily and with firm, clear flesh.
The next round required more of the urchin, an eel roll, red snapper, and more O-toro. I have found it difficult to find fatty tuna in Chicago, so when it's in I tend to indulge. The eel was good, but nothing out of the ordinary. I would say on par with any other, less expensive sushi restaurant. I mean, it's eel. There's only going to be so much nuiance with a bbq'ed, sauce-coated dish. Still, given the excellence of the previous dishes, I was hoping for a bit of flair. No luck. The snapper was delightful, but similar to the eel, seemed less impressive than the previous sashimi. Not bad by any means, just not noticably superior. For desert, we went with mochi icecream- not a stellar choice. In fact, downright disappointing. Not that I expect much from such a pedestrian sweet, but it was pretty bad. Avoid.
Along with the meal, we had a bottle of sake (very good, 500ml for about $22), I had a beer and she had a glass of wine. The total bill ran to just over $80. Without alcohol, I would estimate $50 or so, maybe a bit less. Not cheap by any standard, but given the quality of the sushi, I felt that it was money well spent. I would agree with a previous posting that the sushi is as good as Marai, with less of Marai's exotic options. The dining area is nothing amazing- kind of a faux-loft/industrial feel coupled with some uninspired random walls to seperate areas of the restaurant. Add a few waterfall/glass sheet fountains and that's about it. The sushi bar is more impressive: brushed steel and horseshoe shaped, it's large and eye catching. I thought the flow of the space could use some work- we sat in the 'back' room, which felt crowded and tight compaired to the front room, which seemed a bit dark. We ended up in conversation with the table next to us, since we were less than a foot away. It was packed for a Wednesday night, and it felt packed. If you are looking to seriously impress, I'd say stick with Marai. For equal quality food with slightly lower prices and a hell of a lot less elitist hob-nobbery (which has it's time and place), I'd return to Bob San any time.