Don't you think that these feats should be revised ?
For example : Spell Focus for conjuration school is useless, but Spell Focus for Necromancy school is useful.
Here, a houserule inspired by a Dragon Mag' :
Allow the player to choose between 3 differents effects for Spell Focus :
* +1 to the DD of each spell of the school (generic effect) ;
> Useful for Ench., Necro. & Illus.
* +1 to the spellcaster level for duration & effects ;
> Useful for Trans., Abj. & Div.
* On a dice, 1 becomes 2.
> Useful for Evoc. & Conjur.
For Great Spell Focus, the effect is the same, but more powerful (it replaces the effect of Spell Focus, of course) :
* +2 to the DD of each spell of the school (generic effect) ;
* +2 to the spellcaster level for duration & effects ;
* On a dice, 1 & 2 become 3.
PS : sorry, my english is "approximate". : )
