Wife and I took our kids (a bit older) to Puerto de la Cruz on Tenerife in December 2003. A lot quieter than the beer swilling Las Americas. It has the famous parrot park with dolphin and seal shows and is fascinating for the kids. The penguins, enclosed in their own sanctuary (complete with falling snow) are captivating. The kids will love the fact that the sand on the beaches is black (volcanic). Temperatures in December were low to mid 70's (in old money)! Hope this helps, try a google to find out more.