Wizard 20
Polymorph, Shapechange, most of the buffs you care about, True Strike/Wraithstrike, and so on. Plus, Uncanny Forethought lets you make the Sorcadin cry.
Duskblade 6/Ur-Priest 2/Mystic Theurge 8/Contemplative 1/Abjurant Champion 3
I haven't checked if the skills actually work out, but you can probably make it work out if you're willing to blow feats on any number of them that increase class skills. Also, you can abuse the awfully worded Versatile Spellcaster to turn your bajillion Duskblade slots to make up for Ur-Priests complete lack of spells/day. Unfortunately, it doesn't reach the magic 16 BAB, sadly, but Divine Power make upt for it.. It does use a gish in a can, admittedly, but it goes in a different way from expected. Contemplative is there to get Shapechange.
You could go Duskblade 5/Ur-Priest 2/MT 8/Contemplative 1/Dweomerkeeper 4, if you want SU spells.
Or, you could go Binder 1/Archivist 4/Anima Mage 9(Anima Mage suggests making it available to divine casters)/Archivst advancement 6
Honestly, any way to get 9s is the best Gish.