Sorry for not giving more details in my initial posting about our interests or goals for the trip.
First of all the basics, we are looking at Seville because my husband has both hotel points and airline mileage we can use -- and vacation time he has to use or lose by the end of the year. Due to his job, December is the best time for him to travel and Seville was the least expensive of the options we explored in Europe. My husband is fairly fluent in Spanish and our daughter studied in Spain a few years ago and loved her two visits to Seville. Because it is December and a busy time for me, we will only have about one week total for the trip. (Current thought is flying out Sunday to arrive Monday and then leave on Saturday.)
In 2015 we spent a couple weeks in Germany during an October cold spell -- which included bitterly cold days, but we worked to make the best of the weather -- even visiting a Baltic Coast beach town on a very rainy day. We spent a couple of days in Stralsund just hanging out, wandering the city center, and taking it easy. We are more about exploring one place than trying to hit all the highlights of a country on one trip.
I'm interested in any Advent/Christmas activities that might be happening during our time there. I like the beach (grew up on the CA coast) but my husband could care less. He is much more of a foodie than I am. We both enjoy history and tend to spend twice Rick Steve's suggested time in any museum he might recommend. This is why I mentioned Cordoba in the first post. We live near Sacramento, so temps in the 50s would be just like home for us -- actually the current hot, dry Seville weather is just like ours too.
Anyway, I hope some of those details help. Thanks for all the ideas so far.