The town base
Basing in Trinidad's historic core puts you inside the UNESCO town: cobbled streets, Plaza Mayor, museums, markets and the nightly live music on the Casa de la Música steps. You wake among pastel houses and can walk everywhere. Licensed casas particulares here are plentiful and central.
The trade-off is that the beach is a ride away. You visit Ancón as a day trip and return to town for the evening. For travellers who care most about culture, atmosphere and street life, the town base is the classic choice.
The beach base
Basing out at Playa Ancón or near Casilda gives you the Caribbean at the door: calm water, long sand, snorkelling and boats to the offshore cays. Mornings are slow and salty, and sunsets over the sea are the daily event.
The cost is distance from the town's life. Services on the coast are thinner, nightlife is limited, and you need transport — a bicycle, moped or arranged ride — to reach Trinidad for markets, music and museums. For a beach-first, unwind-focused stay, the coast wins.
Or split the difference
Because Trinidad and Ancón are only about a dozen kilometres apart, many visitors don't choose at all. They base in town for the culture and treat the beach as an easy half-day, or split a longer stay between both — a few nights in a colonial casa, a few by the sea.
There is no wrong answer. The town gives you heritage and human energy; the coast gives you water and calm. The proximity of the two is precisely what makes Trinidad such a flexible destination.
Matching the base to the trip
A short first visit usually argues for the town, where the sights, food and music are concentrated and a beach day is easy to add. A longer or more relaxed stay can lean toward the coast, or split between the two to get the best of each.
Season plays a part as well: the strongest beach weather does not always coincide with the most comfortable town weather, and the latter half of the year brings the Caribbean rainy and hurricane season. Whichever base you pick, keep it information-led rather than romance-led, and the choice tends to sort itself out.