One of the fundamental rules of economics is the concept of supply and demand. The more people want something, the more that demand for the product or service drives up the price. Travel is no different in that respect to any other market, with the result that a room in a hotel in any resort in Spain in August is likely to cost twice as much (or more) as the same property does in May. That’s why — if you have the flexibility to do so — you’re much better off restricting your travel to the shoulder-season months. Of course, what constitutes ‘shoulder-season’ will vary, depending on the part of the world that we’re talking about but as far as Europe is concerned, shoulder-season on mainland Spain runs from April to late May/early June but excludes Easter which is peak season. Shoulder season kicks in again once the kids go back to school in September and runs up until the end of October, excluding the period of the mid-term break in October. Peak season in the Canaries tends to be during our winter as they have no competition to speak of in mainland Europe and so, differs from mainland Europe
The bonus that you also get in travelling to any of the European resorts in off season is that prices tend to be lower in the resort; the weather is more equitable (unless you’re a real sun worshipper) and the resorts tend to be much less crowded but not necessarily to the extent that you feel that you’re holidaying ion a ghost town. The two ‘sweet spots’ during the year — at least as far as sun holidays are concerned — tend to be the months of May and September as you get to enjoy the most competitive prices, good (top up your tan) weather and the resorts themselves are not too busy so service is good and prices keen.
So, if you’re not restricted by school holidays; don’t work within an industry that only takes its holidays at a specified time each year (e.g. the builders’ two weeks in August) or you’re retired or self-employed, then it makes perfect sense to avoid the crowds, save some money, not get third-degree burns on the beach and not have to contend with long queues everywhere — including the airport!