To make the most out of your time on the ground, pick your time of year carefully.
I would suggest that you avoid Easter and Christmas, not only are there lots of national holidays but there are also lots of holiday makers visiting which will not only push the cost of accommodation, car hire and flights up but make the roads busier. If you don’t need to visit during those dates then you will unnecessarily be paying more for less.
Further to this, keep an eye on local holidays. This can get confusing.In Spain, bank holidays (a holiday where all businesses close) can be set by the national government, giving the whole country a day off, an Autonomous Regional Government, giving an entire region like the Valencian Community a day off, a Regional authority, like Alicante, or even a municipality, closing the businesses in a single town for the day.
For example, in my local town there is a regional holiday on the 9th October, a municipal holiday on the 11th and a national holiday on the 12th. If those days all fall in the same working week then many locals will take 2 days annual leave in order to get a full week off. Those who are left to man offices on the days that business are open are overloaded with all the week's work and a skeleton staff. AS you can imagine, not much gets done during that week.
You can find a calendar of holidays at all levels using the link below.
Finally, don’t plan a viewing trip during August. Not only is it very hot, busy and relatively expensive, but many businesses across Spain close for the whole month.
The estate agents who are operating will likely be on a skeleton staff and all the other professionals you need, like Lawyers, banks and notaries will also be working reduced hours (if at all).
While August is the traditional month for businesses to close, July is also becoming a very hot month and as such increasingly uncomfortable to be out and about viewing properties. Personally I would avoid planning a viewing trip in July too.
I often get asked if there are seasonal property price fluctuations to coincide with the busier and quieter times in the marketplace however I have never noticed a trend.