My own personal recommendation is on mainland Spain - a mere few hours away from the UK with nice cheap flights via the likes of Easyjet etc. into Murcia. The resort is San Pedro del Pinatar - a smallish, not very commercial resort where the Spanish go on holiday. You will not find loads of English bars. You will not find all day breakfasts. You will not find nightclubs that are banging into the early hours.
What you will find is a resort with only about 8 hotels in it, but with lots of apartments to rent out at very reasonable prices and lots of nice Spanish bars/restaurants. It is on the coast about a 10-15 minute drive from Murcia airport. The town centre lies back from the 'seafront' area - again about a 10-15 minute walk - fabulous market every Monday and plenty of shops, banks, supermarkets etc.
The seafront itself runs for miles from Lo Pagan, through San Pedro and beyond which is part of the Mar Menor. It is famous for its salt flats and fabulous nature reserve complete with flamingos, and whilst approximately 11km in length, there are fantastic walkways all around it and many people hire bicycles locally to access it, all with a beach surrounding it all. The waters in the area are well known for their apparent health benefits and you will find many older Spanish people daubed in the 'mud' and drying off on the causeway as a consequence. The therapeutic properties allege to improve some diseases such as psoriasis, rheumatism, arthritis, osteoarthritis and fibromyalgia.
Its a lovely Spanish resort which is quiet and relaxing. We have stayed there several times now both in apartments and in the Spa Hotel Lodomar Thalasso. This hotel can be found as a package deal through various online travel agents such as Travel Republic and on Trip Advisor always gets excellent reviews. The food is wonderful, the staff are very helpful and the place is very clean - what more do you need? We are going back to this hotel on Sunday for our second visit. I really hope that if you are interested in Spain you will consider this as its our view one of the most relaxing places we have been at very reasonable price.