It's no secret that the time of week affects your opportunities as well. Many people travel home for the weekends from Madrid to points outside. If you're traveling from Madrid, you may consider doing it M-Th, and doing the Granada-Nerja type legs on the weekends. It looks like your total trip being two weeks puts most of your travel during the middle of the week anyway.
From a sheer ticket-buying standpoint, I've never been turned away from the ticket counter anywhere, at any time of year in Spain...however, about 85% of my travel has been to points from Madrid north.
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Ongi etorri!