Abu Simbel Is Impressive, We Were More Thrilled To See Mirage
It's an impressive monument, but not necessary to stay overnight there. Apart from the temples, there's nothing else to stay for. You can complete you visit in couple of 1-2 hours. It takes 3.5hrs to drive there each way, or you can take a flight.
On the way back, for the first time, we saw mirage in the desert, unbelievable. Apparently it happens often, one of the tourist attraction.
Tips for other travellers
To avoid heat, if you go by car, guide usually picks you up even before 5am and return to your boat for lunch.