The most obvious day trip from Apaneca is also the shortest: Concepcion de Ataco is roughly 3 km west along the CA-8, a colourful town packed with murals, craft shops, and weekend food stalls. It is busier and more visitor-facing than Apaneca, which makes it good for browsing, lunch, and a slow afternoon wander before returning to the quieter end of the Ruta de las Flores.
With transport, Los Ausoles north of Ahuachapan is worth the twenty-minute drive. The geothermal field is rough-edged and facilities are minimal, but the steaming mud pools and fumaroles are genuinely strange and memorable. Combine it with the market in Ahuachapan and you have a good half-day out of Apaneca.