My sorcerer has level 18 in the bank, and has yet to swap out extend. I plan on going water savant.
present feats:
toughness
empower
maximize
heighten
spell penetration
greater spell penetration
My original thoughts were to swap out extend (taken at first level) for spell focus: evocation, then take greater spell focus evocation.
The catch is that I expect anywhere from +3 to +6 DCs on my evocation spells that matter (icy stuff). Maybe I should take spell focus: necromancy or something? Enchantment seems much less enchanting nowadays. Force of personality looks ok, but with FoM on mostly, I can't remember needing a better will save.