Hi Patrick. I moved to Seville with my parents when I was 13, and 10 years later they’re still living there. Seville capital can be pretty expensive, noisy, dirty and hot for living. My recommendation would be to look for a chalet, adosado or piso in the suburban Aljarafe region. This area is up on a plateau and therefore somewhat cooler during the summer. Also, most of the pueblos are only a 10 or 15 min drive into the center. Gines, Espartinas and Bormujos are probably some of the nicer places to live.
Try looking for houses on http://www.idealista.com or www.fotocasa.com. Normally the owners post their houses here directly, so you skip the hassle and cost of an agent. There are lots of new “chalets” (individual houses) outside of Sevilla, and not too expensive either.
If you want to get in touch with other English speakers in the area, check out my dad’s Foundation and Theological Center at http://www.fundacionabre.org.
Good luck, and don’t hesistate to ask for more info. Sevilla is a wonderful place to live in.