The best way I can think of to do exactly what you want to do is run with some sort of Bard-gish, or some sort of Adept-gish. Now, you might be thinking, "Adept, WTF is he talking about, that's an NPC class!" True, true, but it's an NPC divine caster class with lots of arcane spells thrown in for good measure, and it's still better than a Fighter is half the time.
The best way to play a Bard-gish sort of character is either to go straight Bard 10/Sublime Chord 10, or to mix it up, but just a little bit, in going with something like Fighter 2/Bard 7/Spellsword 1/Sublime Chord 6/Abjurant Champion 4. You can pick up some interesting feats that synergize with your Bardic Music to make you more viable in combat. You'll get decent bardic music effects (Song of Timelessness is cool), caster level 18, 9th level spellcasting from wizard/sorcerer/bard lists, +15 BAB.
Now, an Adept-gish type isn't really all that hard to work with. If you could get into the Prestige Ranger that could be nice, but for some strange reason Adepts have Animal Trance, but not Calm Animals... other than that there are a couple options for you. Ranger 4/Adept 6/Hospitaler 10 will get you 13th level spellcasting and 17 BAB. Ranger 2/Adept 8/Hospitaler will bring you to 15th level spellcasting and 16 BAB (probably the better option).
I thought of another way to do this, but I'm not sure how good an idea it is. Duskblade 7/Divine Crusader 3/Mystic Theurge 10 will get you 15 BAB, 17th level Duskblade casting, 9th level divine spells (but drawn only from a single domain), and well, that's about it. Doesn't really seem worth it to me, but Arcane Channeling might make it worth it for you, especially if you can convince the DM to give you Arcane Channeling (full attack).
I think there's probably a better way to work with an Adept, I just haven't thought of it. But there you go, for what it's worth. Bard seems to be the best way to go for you. I suggest you look into it.