If you've never been to Madrid, I think it'd be worth flying in/out of there (or at least in to OR out of). Lots of good museums.
I'll have more recommendations on places/possible travel itineraries from home...
How much driving are you comfortable doing, or would you prefer to stay close-ish to SS? Is the south even realistically an option for what you're hoping to do, travel-wise?
I'm of no help; we did the southern Spain tour of Barcelona, Madrid, Sevilla, Cordoba. I'm super jealous though; I've been dying to go back to Spain.
Both Madrid and Barca seem to be about 5 hours from SS, give or take, and I don't really want to get much further afield than that. Assuming that we are driving, which we would like to do, I think that the south of Spain is out on this trip. I'd prefer to not drive more than 3 or 4 hours in any single day, which is why stopping between Madrid and SS (or Barca and SS) seemed appealing.
Given the relatively little flexibility you have as far as being able to spend a lot of time traveling, I'd still recommend going in and out of Madrid and then using some days to just tool around the northern coast of spain. If you and wifey are pretty easy-going and are fine just wandering and seeing what happens, some of those smaller towns can be pretty awesome. I've been to Bermeo/Mundaka/Bakio (tiny towns on northern coast), and it's just gorgeous. Santander is pretty cool, too. I couldn't tell you any restaurant or spot in particular to hit, because when we went we basically just wandered and ate a shit-ton of jamon. There's not a ton of English in bermeo or mundaka, so if language is a huge deal for you it might not be your bag, but the drive to get from SS to Santander would still be gorgeous and worth doing (I think).
If there's any way for you to get down to Toledo, I'd really, really recommend it. Outside of Salamanca (which is probably beyond your reach for this trip... so sad), Toledo was probably my favorite small town. It's so old and so rich with history, and it's touristy enough that english wouldn't be an issue in a lot of places. Plus it's a big spot for silver, so if you wanted to get something pretty that's a good place to do it.
If you were open to drive/tour days, I'd do this to hit Salamanca and Santiago... both AMAZING places:
SS -> Santander
Santander -> Santiago
Santiago -> Salamanca
Salamanca -> Madrid
Damn, the more I think about it the more you should try to hit Salamanca. love that city so much.
Actually when I first started thinking about this trip, Salamanca was my initial thought. I kind of took it off the list once I started thinking that it would be easier to just go to some place directly between Madrid and SS, but it seems that you think it would be worth reconsidering. I know a few people that have been but I don't know much about the city itself other than it is an old university town (looks like it may be a larger version of Coimbra, Portugal, which is a cool little city). I'll add a few hours in the car, but that's not a big deal.
As for the other cities, given the timing, I think Santiago would be out. But Santander could easily be done, as could Bermeo/Mundaka/Bakio, though I think they might be doable day trips from SS (though I don't know what my responsibilities in SS are going to be for the week I am there).
As for language, I'm not concerned in the least. My Spanish, while not fluent, is more than adequate to get me by.
Salamanca is incredible, coming from this guy who studied abroad there (pretty sure lbe did a semester or 2 after me). but the thing with it is, it's off the beaten path unless you're specifically going there. it's west of Madrid and close to Portugal. so most people don't go since it's not on the way between Madrid and places like the Basque Country, Andalucia, Barcelona, Valencia, etc.
true, but this is a big part of why i think it's great (and yes, I studied there fall 06). it's a true spanish city and doesn't have as many touristy influences/concessions.
I mentioned the language thing because you'll also be up around in the basque region and that language is crazy.
One thing I will say for all of these places - regardless of whether or not you're religious, go and visit all the cathedrals. it is so crazy/impressive to see the workmanship and sheer size of those buildings.