Estepona Southern Spain. I'm older than you and it is a lovely spot. Full working town, gorgeous little narrow streets full of flowers and restaurants, a superb paseo (beach paved walkway) that goes on for miles. Easy to get to from Malaga about an hour, and plenty of scope to go to places like the amazing Ronda on the scenic train from San Roque, or on the bus from San Pedro de Alcantara. A direct bus goes to La Linea which is just across the border from Gibraltar and you can walk over, if that's your thing! There are coaches from Estepona bus station to Malaga, Seville, Cordoba and Granada, connecting in Malaga. Long journeys though. You could also go to Malaga and get the train direct. There are so many options. Estepona is a very lively but not full of rowdy stuff at all, quite family orientated, and I haven't seen a full English breakfast yet!
On the other side of Malaga is Nerja, another lovely spot, similar but not the same as Estepona. You can get to the white villages easily like Frigiliana etc. A day trip to Malaga city itself is well worth it. Lovely place, has everything and more.
Still in Spain but up near Barcelona have a look at Tarragona. It's not right on the beach, but is a fabulous big town and very close to Reus airport. The beaches are nearby and include Mont Roig, Cambrils, Salou and La Pineda. You can get the train to Barcelona from Tarragona.