Mumbai is a bit of a mess, but at least I ate some really good food. Going largely on the advice from the board certainly helped and I hope my notes help the next newcomers.
I ate at a former Copper Chimney (the one in Andheri near the airport), which apparently hasn't been a part of the chain in a long time (outdated guide). Now called Signature or something like that. They kept more or less the same menu, and the butter chicken was the best I've had. About 400-500 Rs pp.
Ate at the Indian restaurant at the Intercontinental near the airport. Seemed to specialize in tandoori and various kebabs. A nice, meaty fish was my favorite (forgot the name but it was similar to swordfish). At a really nice hotel, the prices are comparable to your average neighborhood Indian restaurant in the U.S. (with better food) - our most expensive meal at 700-800 Rs pp.
Thali at Rajdhani was good eats and a great deal. A few things the likes of which I hadn't had before included some kind of spiced coleslaw-like dish, banana flavored green beans, and some really great yogurt. Lunch was about 180 Rs pp all you can eat (of course).
Dinner at Apoorva had good and bad points. Didn't spring for the king crab, but got the white crab both curry and tandoori. Good, but I don't really recommend the curry version - with the sauce all over it, it's just really hard to eat. Also, this crab didn't taste as fresh - maybe they hide the older ones in the curry, or maybe it just wasn't that good to begin with. Squid with chili garlic sauce had great flavor and was some of the most tender squid I've had. 400-500 Rs pp for too much food.
Everywhere we ate, the vegetable dishes really impressed me. I recommend getting your fill of seafood *before* any boat rides on the harbor (i.e. Elephanta Island), or just avoid any boat rides altogether.
Read about the first leg of the trip (London) here: