You MIGHT be interested in my
MadridMan's 2002 Madrid & Galicia Trip journal entry - from way back from before blogs were around and STILL in the MadridMan.com Version 1.0 stage. Wow. I need to get on that soon. There aren't any photos, but I still have a bunch from my first digital camera which I took on that trip. What a wonderful experience I had in Galicia.
If you decide to "do" Madrid and Galicia, that's great. You'll have enough on your plate for these two locations/regions. Really, Galicia has enough to see for your entire 3-weeks alone, but you could do it justice in just 7-12 days. You can always visit Asturias, Cantabria, and País Vasco another time. For THAT you'll need 3 entire weeks!!!
Regarding the beaches and topless-ness, Spain's beaches throughout the country are considered "Topless-Okay" (thank goodness!!!) so that's not a worry. It's not expected, however, so any on-top-wearers shouldn't feel self-conscious. It's not illegal and it's not considered "bad form" to go topless in Spain, even at the city's public swimming pools. (I LOVE THIS COUNTRY!!!!
: )
We did the drive from Santiago de Compostela to Madrid in one long-ARSE day by car. Wow. What a journey! According to Google Maps, that's a 7.5 hour drive -without stopping! We stopped like 3 times along the way for meals and "pit-stops" so it took us about 9 hours.
Traveling town-to-town probably isnt' conducive to renting apartments, but you should be able to find - online - several decent "hostales" in some off-the-highway towns to spend a comfortable night. This'll take some research, however. The ON-highway "hostales" don't tend to be very nice. That is to say, they're basic and generally clean, but lack character and can often be havens for truckers' one-night-stands - if you know what I mean. Best to get 5-10 kilometers off the highway to find nicer, more local lodgings.
I'M excited for your visit/trip, teachertraveler8! O hope to see you while you're passing-through Madrid!
Saludos, MadridMan