Shadowcraft mage (Races of Stone), even without much optimization, makes a powerful and thematic illusionist.

Master Specialist (Complete Arcane) is great for both the enchanter and illusionist, with the enchantment esoterica suppressing many of the bonuses charmed or dominated foes get on their saving throws and the illusion esoterica providing a flat (and large) boost to save DCs. Master Specialist also provides Greater Spell Focus for free, which is good since both of these schools rely heavily on failed saves to work properly.

For the evoker I'd recommend a metamagic-focused route. For prestige classes there's the obligatory mention of Incantatrix (Player's Guide to Faerun), but straight wizard does pretty well, too, especially since your BBEGs are 10th level (for that extra metamagic feat). It's easy enough to pick a bread-and-butter damage spell or two, grab Arcane Thesis and similar metamagic reducers, and go to town. For details, I'll just point you to the Mailman build.

Speaking of metamagic, don't forget to include Quicken Spell so that each wizard can make the most of the 4-6 rounds he'll have to tussle with the PCs.