A week will barely suffice to enjoy this region, with the bulk of your time centered on Trinidad [1]. The town itself needs two full days for exploring the colonial sites. However, the Trinidad experience is more about slowing down and immersing oneself in the local life, so a full week here should not be considered too much.
Budget one day for an excursion to Topes de Collantes [2] to hike mountain trails and go birding.
You’ll want beach time, too, so plan one day for sunning, snorkeling, and perhaps even scuba diving at Playa Ancón [3]. If you prefer the company of Cubans, head to La Boca [3], where locals flock on weekends. A steam-train ride from Trinidad to the Valle de los Ingenios [4] is also de rigueur.
Víazul buses [5] operate daily to Trinidad [1] from Havana [6]. Organized excursions are offered from almost every other tourist destination in Cuba.
The city of Sancti Spíritus [7], which is well served by buses, deserves at least half a day’s exploration; you’ll be hard-pressed to find more than a full day’s worth of things to see and do. Bird-watchers might consider a visit to nearby Embalse Zaza [8], a vast wetland where the fishing for bass and tarpon is world-class.
The Autopista runs 15 kilometers north of the city and continues east for 20 kilometers before ending abruptly in the middle of nowhere, near the city of Jatibónico.
The Circuito Norte cuts across the northern province inland of the coast, which has no beaches of appeal. Nature lovers, however, might get a thrill at Parque Nacional Caguanes [9], although there are no facilities and getting there is difficult. Interested in revolutionary history? The Complejo Histórico Comandante Camilo Cienfuegos [10], nearby at Yaguajay, is one of the better provincial museums.
Links:
[1] http://www.moon.com/destinations/cuba/sancti-spiritus-province/trinidad
[2] http://www.moon.com/destinations/cuba/sancti-spiritus-province/trinidad/trinidad-excursions/gran-parque-natural-topes-de-collantes
[3] http://www.moon.com/destinations/cuba/sancti-spiritus-province/trinidad/trinidad-excursions/la-boca-and-peninsula-de-ancon
[4] http://www.moon.com/destinations/cuba/sancti-spiritus-province/trinidad/trinidad-excursions/valle-de-los-ingenios
[5] http://www.moon.com/destinations/cuba/essentials/getting-around/bus
[6] http://www.moon.com/destinations/cuba/havana
[7] http://www.moon.com/destinations/cuba/sancti-spiritus-province/sancti-spiritus
[8] http://www.moon.com/destinations/cuba/sancti-spiritus-province/sancti-spiritus/sancti-spiritus-excursions/embalse-zaza
[9] http://www.moon.com/destinations/cuba/sancti-spiritus-province/sancti-spiritus/sancti-spiritus-excursions/parque-nacional-caguanas
[10] http://www.moon.com/destinations/cuba/sancti-spiritus-province/sancti-spiritus/sancti-spiritus-excursions/monumento-camilo-cienfuegos