In Chennai, I stayed at the Chola Sheraton. I had a very nice suite, which was noisy during the day but quiet enough after traffic died down after rush hour. Not cheap, but a far better value than the Ashok in Delhi. Its good to know that it used to be Hotel Chola (thats what most taxi drivers know it as).
Spencer Plaza is an incredible multi-level shopping mall. You can find anything, including the standard tourist trinkets. Due to heavy competition and the urban environment, it was extremely easy to get a very good price on the standard souvenirs (marble inlay boxes, elephants, etc.) that you see most places in India. A good chance to eat safe Indian "fast food", as well.
I had a slight camera emergency (my digital camera battery went from half full to empty in two pictures). In the US, that would mean getting a disposable camera. While some of the wedding guests had heard of a disposable camera, they are by no means common. Ten or more convenience, grocery, and other stores hadn't a trace. In a photo developing place, they had two low-end cameras on display ($10). Unfortunately, they had none in stock but could get me one tomorrow. After some discussion, they agreed to deliver it to the wedding hall in 90 minutes.
As the only person at the wedding with a camera (apparently Indians don't see the point with a professional photographer present), the other guests were surprised when I got a second one delivered in the middle of the ceremony. Oddly, getting a delivery then isn't nearly as rude as it sounds -- during the vast majority of the ceremony people were getting up, talking, drinking water, children were playing, etc. Fortunately, being the only white person there, I was relatively easy to find in the crowd.