Spain & Portugal in late December/early January

I agree with Rick on most things, but he's unfair to the Costa del Sol and to Tangiers.
There are lots of activities to keep you going during a trip to that area. Yes, it is built up and, no, it is not the ancient Spain of Rick's dreams...but hey, this is the 21st century. The old section of Malaga Rick completely ignores, but it makes for a really nice day tour. Some of the villages to the west of Malaga remain as they were, and the drive is quite scenic.
The Costa itself makes a good base for day trips into the mountains to the north, and at that time of year, you should get excellent deals on accommodations at the resorts that line the coast. Mijas Pueblo, Ronda, Grazalema, Zahara, and the like are all within easy range. It's a longer trip, but Granada is also do-able in a day.
As for Tangiers, Rick's description is in error, completely ignoring the history of the city. As opposed to Tijuana, which exists as it is only because of the influence of visitors from north of the border, Tangiers has a long history as a very international city. From the original Berber founders, through the Phonecians, the Romans, and the Arabs, the city has grown into a modern trading center. Over the past five centuries, it's been controlled by the Portuguese, the Spanish, the British, and the French at various times, as they used the city as their main entryway for trade and diplomacy into northwestern Africa. All of these past rulers have left their imprint on the city. In spite of all that, you will still find the old city and its narrow alleyways an attractive place to visit. Is it the Morocco of "Casablanca" movie fame? No, it is not, and never has been. Is it an interesting place to visit for a day....yes.

We spent a week in Spain over New Year's last year. Here's our report in blog form, if it helps! http://moltogentileitalia.blogspot.com/2009/01/report-from-spain.html