No need for night stops abroad, just overnight flights, 10PM departure from SOU, 2-3 hour flight, hours turn around and then back to SOU for the first landing of the day circa 6AM. The plane would then be available for a 7AM departure.
When the E170 arrive it would be nice to see BCN on the SOU route map. Other potential destinations maybe FCO, MXP, MUC and CPH