It is impossible to give a definitive answer since I do not know you or your children. But here are a few things to consider in making your decision.
Can you depend on your children to stay in the room with the door locked? Are they mature enough to not create a disturbance? If hotel employee knocks at the door, are they mature enough to call the front desk and ask for identification?
How late do you plan to be out? If you are planning to dance and drink until 3 am then it might be best to hire a sitter, even if you have a cell phone, as you may be distracted and not answer it. Imagine you were the subject of a newspaper story involving inebriated parents out dancing while someone broke into there hotel room.
The worst case scenario would be in case of fire. The odds of that are probably lower than winning the lottery, although it might be worthwhile to agree on a meeting spot outside the hotel just in case your children would need to abandon the room in an emergency.