This would be an unarmed build for fastest attack speed to use Sneak Attacks.

Looking back at it, I probably put points into Dex at level ups instead of str and grab Weapon Finesse instead of Power Attack. Also change the initial stats to 12 str and put those points into Dex/Con. Let me know what you think

Code:
Character Plan by DDO Character Planner Version 3.10
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Level 20 Lawful Good Drow Female
(1 Monk \ 19 Rogue) 
Hit Points: 206
Spell Points: 0 
BAB: 14\14\19\24
Fortitude: 9
Reflex: 19
Will: 7

                  Starting          Feat/Enhancement
                 Base Stats          Modified Stats
Abilities        (Level 1)             (Level 20)
Strength             16                    21
Dexterity            16                    23
Constitution         12                    12
Intelligence         16                    18
Wisdom                8                     8
Charisma             10                    10

Tomes Used
+2 Tome of Dexterity used at level 8
+2 Tome of Intelligence used at level 8

                  Starting          Feat/Enhancement
                 Base Skills         Modified Skills
Skills           (Level 1)            (Level 20)
Balance               7                    29
Bluff                 0                     6
Concentration         1                     1
Diplomacy             0                     0
Disable Device        7                    27
Haggle                0                     0
Heal                 -1                    -1
Hide                  7                    37
Intimidate            0                     0
Jump                  7                    28
Listen                3                    24
Move Silently         7                    37
Open Lock             7                    29
Perform               n/a                   n/a
Repair                3                     4
Search                7                    29
Spot                  3                    24
Swim                  3                    13
Tumble                7                    29
Use Magic Device      4                    23

Level 1 (Rogue)
Feat: (Selected) Toughness


Level 2 (Monk)
Feat: (Monk Bonus) Power Attack


Level 3 (Rogue)
Feat: (Selected) Two Weapon Fighting


Level 4 (Rogue)


Level 5 (Rogue)


Level 6 (Rogue)
Feat: (Selected) Toughness


Level 7 (Rogue)


Level 8 (Rogue)


Level 9 (Rogue)
Feat: (Selected) Improved Two Weapon Fighting


Level 10 (Rogue)


Level 11 (Rogue)
Feat: (Rogue Bonus) Cripling Strike


Level 12 (Rogue)
Feat: (Selected) Weapon Focus: Bludgeoning Weapons


Level 13 (Rogue)


Level 14 (Rogue)
Feat: (Rogue Bonus) Improved Evasion


Level 15 (Rogue)
Feat: (Selected) Improved Critical: Bludgeoning Weapons


Level 16 (Rogue)


Level 17 (Rogue)
Feat: (Rogue Bonus) Slippery Mind


Level 18 (Rogue)
Feat: (Selected) Greater Two Weapon Fighting


Level 19 (Rogue)


Level 20 (Rogue)
Feat: (Rogue Bonus) Defensive Roll
Enhancement: Rogue Damage Boost I
Enhancement: Rogue Damage Boost II
Enhancement: Rogue Haste Boost I
Enhancement: Rogue Haste Boost II
Enhancement: Rogue Haste Boost III
Enhancement: Rogue Haste Boost IV
Enhancement: Rogue Skill Boost I
Enhancement: Elven Dexterity I
Enhancement: Elven Dexterity II
Enhancement: Rogue Subtle Backstabbing I
Enhancement: Rogue Subtle Backstabbing II
Enhancement: Rogue Subtle Backstabbing III
Enhancement: Rogue Subtle Backstabbing IV
Enhancement: Disciple of Breezes
Enhancement: Rogue Faster Sneaking I
Enhancement: Rogue Faster Sneaking II
Enhancement: Rogue Assassin I
Enhancement: Rogue Assassin II
Enhancement: Rogue Assassin III
Enhancement: Rogue Sneak Attack Accuracy I
Enhancement: Rogue Sneak Attack Accuracy II
Enhancement: Rogue Sneak Attack Accuracy III
Enhancement: Rogue Sneak Attack Accuracy IV
Enhancement: Rogue Sneak Attack Training I
Enhancement: Rogue Sneak Attack Training II
Enhancement: Rogue Sneak Attack Training III
Enhancement: Rogue Sneak Attack Training IV
Enhancement: Rogue Hide I
Enhancement: Rogue Hide II
Enhancement: Rogue Move Silently I
Enhancement: Rogue Move Silently II
Enhancement: Rogue Dexterity I
Enhancement: Rogue Dexterity II
Enhancement: Rogue Dexterity III