It depends on the age of your children:
1) Children above 12 are considered as an adult by law, and no discounts are given.
2) Children under 12 get 50% off for the flight booking. While for hotels, it charges nothing in sharing existing beds, and extra charge for extra bed.
3) Infant less than 2 charges only 10% of the flight ticket, while free baby cots for babies in hotels.