comrade raoul
Explorer
I'd contemplating a quick and simple change to immediately apply when I get my 3.5e books. What if, drawing on the law of diminishing marginal utility, Spell Focus gave a +2 bonus to DC, but Greater Spell only gave an additional +1? That way, you do take some steps to keep saving throw DCs under control, but you also make both feats somewhat more worthwhile and create interesting choices: the mage who decides to maximize the DCs of his favorite school will still happily take both feats, but casters also have real incentive to diversify.