Actually Seriphim, Sacred Summons works when you summon a monster with the exact same SUPTYPE as your DEITIES alignment.
Looking at the summon monster lists, that means 3, 4, 7, 9 for LG; 3, 7, 9 for NG; and 3, 5, 6, 9 for CG.
If you're going the evil route, it gets a bit better with 2, 4, 5, 6, 7, 8, 9 for LE, and 3, 5, 6, 7, 8, 9 for CE.