Right behind Estepona is Los Reales de Sierra Bermeja which offers amazing views to the entire Andalusian coastline, and you can even see all the way to Gibraltar and Morocco. And what is best, you can get to the viewing platform by car, so no need to hike unless you want like we did.
We ended up doing a hike of approx. 7 km in length and with 450 m of elevation. The hike took us through some amazing scenery and round the top of the mountain. The trail was mostly well marked except at few spots where you really had to look for the signs.