The buses from Lagos to Seville terminate at the Plaza das Armas Bus Station on the the southern edge of the Central Business District.
Unfortunately, several hostels and hotels in the area have been demolished recently. When I now go to Seville I stay at the IBIS on the road to the airport (Avda. Kansas City) as parking is a pain in the centre.
You can find a list of hotels hear:
http://www.sevillaonline.com/hoteles/index.html
Also look here:
http://www.trav.com/wri-10952/HotelAacrMuseo
and
http://www.trav.com/Hotels/Spain/Seville
