If you want full spellcasting, then Wizard(10) or Sorcerer(10) with EK(10) is the way to go. If you're willing to give up 9th level spells, then you can do Pally(2)/Sorc(8)/EK(10) for the bonus to saving throws.
Personally, I like my Wizard(5)/Fighter(6)/EK(9)... 7th level spells with 3 bonus fighter feats. Still casting as a level 17 wizard, so all the buffs last a good long time. --- "I have an idea. It starts with 's' and ends with 'litting their throats.'" ~Belkar from The Order of the Stick
Sorc6/EK10/HarperAgent 4, cast as an 18 sorcerer (level 9 spells), 4 attacks/round (so you fight almost as well as a pure warrior), and you're quite nukey. It's a bit intensive on feats and skill points but the results can't be argued against. Probably best used with sword and (mithral heavy) shield style, since most of your damage will be coming from enchantments instead of the actual weapon you'll be using. --- I wish for this night-time to last for a life-time
Are you taking this character into the expansion? I made a really cool character who can pretty much do it all. My first level was rogue for the skills(then I got able learner right away) then I leveled in wizard until I could take EK levels. My final build was Wizard 10/Eldritch Knight 10/ Rogue 10. Then get that feat that allows you to apply your Int modifier to your damage and the guy rocks. He can cast 9th level spells, open locks, disable traps, and can average a great deal of damage each round with melee. Also his AC was somewhere in the 50's with just equipment. Pretty good for a wizard. --- Favorite Guitarists: John Mayer, Henry Garza, Mato Nanji, Eric Clapton, Jeff Healey