Alajuela [1] is curiously devoid of noteworthy restaurants.
Jalapeños Comida Tex-Mex (Calle 1, Avenidas Central/1, tel. 506/2430-4027, 11:30 a.m.–9 p.m. Mon.–Fri., 11:30 a.m.–10 p.m. Sat.), on the west side of Parque Central, is a cheerful place offering great bargains on eggs ranchero, omelettes, and nachos (made with fresh corn flautas). I recommend the spicy sopa Azteca ($2). The hosts, Norman and Isabel, are delightful.
Ambrosia (Avenida 5, Calle 2, tel. 506/2440-3440, 10 a.m.–7 p.m. daily) offers a pleasantly airy ambience for enjoying Costa Rican fare and Italian dishes, including four types of lasagna. Great batidos (milk shakes).
In Río Segundo de Alajuela, the Calalú Typical & Caribbean Food Restaurant (tel. 506/2441-2121, 7 a.m.–8 p.m. daily) is a great place for shrimp in Caribbean sauce ($10), grilled chicken breast ($7), and coconut flan. It also serves casados ($5).
Seeking a delightful little coffee spot? Then head to the clean and airy Trigo Miel (Avenida 2, Calles Central/2, tel. 506/2442-2263, www.trigomiel.com [2], 7 a.m.–8 p.m. Mon.–Sat., 8 a.m.–6 p.m. Sun.), which has WiFi. And you can buy baked goods at Musmanni (Calle 8, Avenidas Central/1, and Calle 9, Avenidas 1/3).
Links:
[1] http://www.moon.com/destinations/costa-rica/central-highlands/alajuela-and-vicinity/alajuela
[2] http://www.trigomiel.com