What kind of villas do you prefer?
Getting an idea about the layout, the floor plan and the type of villa you are getting into is very important. If you want an experience of Spain, villas that are slightly more traditional in the mannerisms including the architecture are a better option. If you are looking for absolute luxury, the standards are pretty much same across the world and you will have to go for a beachside villa that offers you great comfort and magnificent views.
The location
Perhaps the location of a holiday villa in Spain could be amongst the most important factors whilst choosing one. Some holiday villas are located deep away from the major stations and airports. In such cases, you might need to hire a car to take you around. More importantly, ensure that you reach such villas before it is too dark as the roads could be nasty and often badly signposted. The safety of the villas and the route that leads to them also needs to be a primary concern if you are heading for a holiday with your family.
Basic needs
Sightseeing is your primary motive, so ensure that your villa is not too far away from important attractions. You should also ensure that there are restaurants nearby, if you want to eat out of the villa for a meal or two.