for various reasons, we are using Madrid as a base/rented apartment for a week. Aside from Toledo, which are the best day trips from Madrid? First visit to Spain for a mom and grown son doing his grad work in Germany. History, food and culture, wine and photography are interests for us both, and I adore architecture and he would like to get out at night, not doubt (at 26...I would have). Thanks
El Escorial is great. I assume you will visit the Prado.. Velasquez portraits are wonderful and you can see where the royal family from those days rest in the mausoleum at El Escorial. Nice tie in between the history and art in Madrid. Add to that the royal palace in Madrid to complete the picture. Also Segovia is a great day trip. The Roman aqueduct there is second only to the the Pont du Gard in Provence among the ones I have seen. It's also a very nice town. Don't focus so much on day trips that you miss Madrid, beause the city has a lot to offer as well.
Cordoba would be another easy daytrip if you're based in Madrid. The Mezquita is amazing and worth the trip alone. But it would also give you a taste of Andalucia and the great mix of cultures that occured in Spain prior to the reconquista.
El Escorial, Segovia, La Granja de San Idelfonso, Avila, Aranjuez, Cuenca and a little farther out but doable if you have a car or if you overnight in Toledo is the town of Consuegra. Madrid is a great base because there are so many interesting sites nearby. Do some research and see if any of these places appeal to you.
If you head up to El Escorial, I highly recommend taking the public bus up to The Valley of the Fallen, which is about 15 minutes away. Only one bus goes up there, and it leaves at 3:15 pm and returns at 5:30. Very few tourists go up here. This is described well in the guidebook. The monument is very serene, and a nice break from Madrid. We enjoyed this sidestop even more than the monestary at El Escorial.