It seems to be impossible to get Google Maps to do what the API reference says it should do automatically: zoom a map to the bounds of a KmlLayer. I've ended up specifying default zoom layers of 16 for single places and 13 for multiple places for the moment. I've also looked at trying to display labels for places in a KmlLayer, but that's not supported, even though the mechanisms for doing it are available (there is a <LabelStyle>, but setting it has no effect, and this is even true in Google Earth AFAICS). Very disappointing API implementation.