Re: how do you travel to/from the airport at destination?
India is a huge country. Pakistan is much smaller, and the longest train ride is perhaps a bit more than 24 hours, and bus ride, about 36 hours. I once took Daewoo from Karachi to Bahawalpur and that took about 14 hours. After that, I vowed never to take a bus ride longer than 3 or 4 hours. Despite numerous rest stops in between, bus travel is gruelling, and the beating that your legs take is just not worth it. Now if you are talking about sleeper buses, that is different, and could be interesting.
However, generally, if I have a choice between bus and train, I prefer trains, as the scenery is far more enchanting, the interaction with other passengers is more personal, and the train stops are feature rich.