Disclosed are lid assemblies for use on a vessel holding a base liquid. They include an agent chamber for holding a liquid agent and a pivotable spout. The spout includes a base liquid inlet port and a liquid agent inlet port, respective passageways connected to those ports and terminating at a mixing space. The agent chamber includes plural different sized metering orifices, orifice configured to be brought into communication with the liquid agent port of the spout when the spout is pivoted to any one of plural angular positions to provide a metered amount of the liquid agent into the spout for mixing with the base liquid in the mixing space when the user sucks on the spout. The base liquid is drawn into the spout from the interior of the vessel via a base liquid metering port that is brought into communication with the base liquid inlet port when the spout is in any one of those plural angular positions.