I visit Karachi a fair bit (great city for food, incidentally!). My preferred route is via Muscat, Oman, because the connection works well and/or an excuse to stay over in one my other favourite locations in MCT. DXB is another option too. Obviously you can't do this wholly via oneworld, but it works well for me.

In Southern India my favourite spot is the largely Catholic city of Mangalore, (and yes there was a nasty crash at the airport there a few years back) but Kerala is both fascinating and awe inspiring.