Marinel is a host that I highly recommend. she gave me a map of the city center, a book of the best restaurants in the city and several advices (free flamenco place, museums to avoid).
The apartment is small but very functional and clean. It is very well located, very central ! It's a pedestrian area. Everything could be done by walk. No problem to hang out safely at night.
I arrived from the airport by bus (AE - 4euros). I went down to the Torre del Oro station and had 15 min pleasant walk through Avenida de la Constitucion, plaza nueva, plaza de Salvador. Very nice place !!