The Shulchan Aruch prohibits having relations if there is somebody else in the room who is awake. If the other people in the room are sleeping, then relations are permitted. However, it is permitted to have relations if there is a baby who can not yet talk (i.e., active, descriptive talking) in the room, even if he is awake.
Therefore, it is certainly permitted to have relations in a hotel room with a sleeping toddler in the room.