The route moves in one direction from Lisbon to Porto, so there is no wasted return journey. Three nights in Lisbon cover the centre, Belém and a full Sintra day without changing hotels. Coimbra then earns one overnight rather than a rushed luggage stop: the University of Coimbra controls entry to the Baroque Library in timed groups, and the current library programme is valid for two days. Two nights in Porto leave one arrival afternoon and one full day before departure. The compromise is pace. Lisbon and Porto could each justify longer stays, and this plan excludes the Algarve, Évora and the Douro Valley. CP's limited Promo allocation can reduce the rail cost when bought at least five days ahead, but the safe budget is the current full-fare total shown by CP, not the lowest advertised seat. Travellers with limited mobility should also budget for taxis in the steep historic centres rather than assuming every hotel-to-station transfer is walkable.