I did this Bahrain Dahran route once (737, not 747) when connecting into Saudi with Gulf Air (pre causeway). After boarding the plane, we sat at the gate while they served the "in flight " meal, then they closed the doors started the engines and off we went. Time in the air can't have been much over 10 mins if that.
Then the fun started with Dahran immigration (2 hrs standing in a queue on the tarmac (fotunately nighttime) before even making it into the terminal building, all in I guess 4 hrs to clear immigration & customs).
After the causeway opened we used to check in at a Dhahran hotel and get bussed over the causeway by British Caledonian to meet their Far East DC10 (full of the living dead on thier way back from Australia).
PIA used to regularly fly 747 between Islamabad and Karachi (I remember havig to wait two days for my suitcase cause they couldn't open the baggage door in Islamabad so had to fly back to Karachi with it). Absolute dog of a 747, overheads held together with duct tape etc.