Congratulations! You'll have a wonderful time in Iberia. For a 12 day trip, I would take 3 pairs of pants, 4-5 tops, and 2-3 pairs of shoes (I'm female). Take a travel-sized bottle of Febreze with you and you'd be amazed how often you can re-wear something with no problem. You can always wash out socks and underwear in the sink, but I'll confess I tend to pack a ton of both. A 4 star hotel should have some kind of laundry service, but even if your hotel doesn't they can always hook you up with someone locally. I suspect that once you're actually on the trip, laundry will be your least concern. Enjoy!