I basically agree with Moridin's assessment, with a couple of additions:
1.) With Wands of Spell Striking, you don't even need Mages for removing spell protections any longer. A thief with "use any item" special ability or a Bard will suffice.
2.) I'd suggest that you set up one of your Mages as the "Summoner". Have him/her capable of summoning all of your monsters (i.e. Skeleton Warriors, Spiders, Invisible Stalkers, Elementals, etc.). I also like to use Imoen in this manner...she sneaks up on groups of enemies that I anticipate to be difficult (utilizing the Staff of the Magi) and blasts them with area of effect spells, then goes invisible again before she can be attacked. Cheese? Maybe...but effective cheese, none the less!
3.) I also don't really see the use for mages' Haste spell capabilities anymore as I'm currently up to 5 pairs of boots of speed and one set of Leather Armor +6 that works like Boots of Speed (Valgyar wears this).
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Now where did I leave that doughnut?!