The previous over-developed comment doesn't relate to the whole of the Canaries, although this would apply to parts of Gran Canaria and Tenerife.
Staying at El Cotillo on the west coast of Fuerteventura (Canaries) sounds as though it would fit the bill! It retains its traditional feel and hasn't been over-developed. Fuerteventura has the best beaches in the Canaries. The sandy beaches are great and there are walks out to the lighthouse or you can rent bikes or segways. The beaches to the north of the village are quiet, as they are protected by a reef, whereas the beaches to the south are for surfers, where there is no reef. There is a good bus service if you don't want to hire a car. The volcanic scenery is amazing in the middle of the island - visit Betancuria, the old capital.
You certainly don't need air conditioning at any time of year on Fuerteventura, as there is a cooling breeze. I was in the sea there in November, so it will be warm enough in the summer. You can take a day trip to neighbouring Lanzarote or the marine sanctuary around Lobos island.
Madeira is more temperate, being c 18/20 degrees all year round and wetter and there aren't really any beaches there. The walking is good.
I found that Malta had too much development and the food was disappointing compared to other places. Corsica and Sardinia need 2 weeks to explore, as they are larger. Minorca is quieter then Majorca, but to escape the crowds, you need to stay inland. Ibiza in the summer is party central. The Balearics will be hotter than the Canaries.
