Ideally, I'd also have Full BAB, good Hit Dice (i.e. > d8), all good Saves, 6+Int skills (if not better), maneuver progression, and whatever class features I can pick up.
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As far as combat goes, I'd like to be a highly mobile damage dealer and fear monger, with the feats to play a charger/jack-be-quick type fighter.
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I'd also like to be able to strike fear into my enemies since it was that or spiked-chain tripping for battlefield control.
Warblade 20 // Factotum 20 // XYZ 20
Covers the first bit completely, except for the will save. You have 20 levels perhaps filled with oodles of multiclassing to fix that. Your base will save could easily get more than +12 at level 20. Just pick 2 or 3 classes with a strong will save for the third side and you'll be golden.
For the love of Odin, do NOT forget Iron Heart Surge or White Raven Tactics. Those two maneuvers might be your best and the
best maneuvers in the entire book and all Warblades learn them at level 5 and level 6 (one just by learning, the other by trading an old maneuver), agonizing over choosing which comes first. This is not a statement of opinion, it is a fact. You will learn Iron Heart Surge and White Raven Tactics if you don't want to give me a blood clot.
Sudden Leap (Tiger claw 1st level boost, Tome of Battle) will cover low level mobility very well until something from your third side kicks in. To get that desired mobility, you have 20 levels to play with. Might I suggest Swordsage (for the Shadow Jaunt, Shadow Stride, and Shadow Blink maneuvers + other less easily memorable but still mobility granting abilities/maneuvers)? There are also teleporting classes galore and they all love shadow pounce from Telflammar Shadowlord (Prestige Class, Unapproachable East, page 36) which gives you a full attack at the end of every teleportation ability you use. Prestige Classing into Horizon Walker for 6 levels (Prestige Class, Dungeon Master's Guide, page 189) to get the Shifting Planar Terrain Mastery to get Dimensional Door once every 1d4 rounds (more than 400 feet teleportation) should be considered a low water mark for a mobility fighter using teleportation for mobility. Shifting Planar Terrain Mastery is like burst of waterfall while all you need is a constant steady stream of short ranged teleportations. You can do better.
As for fear, there is a fear handbook:
http://brilliantgameologists.com/boards/index.php?topic=3809.0 . It will explain much better than I. One rather potent trick is Intimidating Rage + Instantaneous Rage (Both Complete Warrior, feats) + Imperious Command (Drow of the Underdark, feat) + Never Outnumbered (Complete Scoundrel, skill trick) to cower everyone in range who fails your immediate action intimidate you can use on someone else's turn. Evil Wizard casting save or die? Nuh-uh, I Rage, Intimidate everyone, and he's cowering on the floor along with all his minions. Cowering makes you lose all your actions FYI. This combination is lovely.
You'll have the feats for Robilar's Gambit and Karmic Strike, or uber-charging, but probably not both. Choose one and stick with it. You're either a charge monster or a blender set to liquefy. For the Blender option, I would also suggest a lockdown build so enemies can't escape the blender (you). We call lockdown + Jack B. Quick a crackdown build (an inescapable blender). The staples are reach (Spiked Chain says hello from the PHB for the 1000th time), Stand Still (nonpsionic feat, Expanded Psionic Handbook), Combat Reflexes (PHB, feat) so anything trying to get away just stands still. Add Improved Trip + tripping attacks if you really want (those rely on a high strength and size category, though. Stand Still just relies on huge damage. Your huge, huge damage.).
This part of a handbook will explain crackdown builds:
http://brilliantgameologists.com/boards/index.php?topic=357.msg6904#msg6904 . It uses Crusader and Tome of Battle material.
We have
two charging handbooks:
http://brilliantgameologists.com/boards/index.php?topic=7200.0 and
http://community.wizards.com/go/thread/view/75882/19872838/Little_Red_Raiding_Hood:_A_Tale_of_38;_Guide_to_the_3.5_Dragoon both of which will tell you everything you need to know.
Excuse my late night grammar. Hopefully you can understand my original and unadulterated meanings via contextual clues located near grammatical/spelling errors.