Chennai is not really the sort of place where you would want to spend a couple of weeks. Sure there is a beach, but it is not a resort and a day or two is long enough to see the (limited) sights. Mahabalipuram, an hour to the south, is more interesting. Fascinating historical sights, and some nice resort stayle hotels. It's still not a place for a beach holiday though. Pondicherry, a couple of hours further south is also worth seeing. But nowhere on the East coast can really be compared with Goa - the sea is rough so swimming is inadvisable, there are no beach shacks, bars are expensive and only in hotels (excpt Pondicherry, which is well known for cheap booze).