Alajuela is the second city of the Central Valley and the one almost every visitor passes through without noticing, because the international airport is on its edge. It is worth an hour: a hot, low-rise, genuinely working town built round a mango-shaded central park, with none of San José's edge.
The town is proud of Juan Santamaría, the drummer boy from here who in 1856 set fire to the building William Walker's filibusters were holding at Rivas and was killed doing it, ending the invasion; the museum in the old jail tells that story, and the airport carries his name.
Practically, it is a better first or last night than San José — fifteen minutes from the terminal rather than an hour in traffic — and it is the gateway to Poás, forty minutes up the mountain.