Colombo
The arrival city. Gangaramaya, a proper night if you want one, and the airport within reach.
Most trips touch Colombo because the main airport is next to it, at Katunayake. That does not mean you owe the city a day. If the flight lands late, sleep nearby and leave in the morning. If you want the city, give it a night of its own.
The signature escape does that on purpose: a last night in Colombo, an executive suite in the published sample, and Gangaramaya among the visits. The pilgrimage sample starts here as well. We do not pad a beach week with a city tour just to say Colombo was included.