I can't vouch for the walking, but the site-seeing is BRILL! My top recommendation is to spend some time in Seville...a totally awesome place, just lovely! Great bars, great food, all excellent. Fantastic Cathederal, good shops and the locals are all very friendly.
Top tip for those spending any time anywhere in Spain is to expect to eat late in the evening, as most Spanish don't normally have dinner til about 9pm at the earliest.