Herobizkit
Adventurer
I'm gonna agree with everyone else and say 2 levels of Fighter will give you the staying power to stay toe-to-toe with the other melee classes should your sneak attacking go sour. Plus, you get a better weapon selection.
As an aside, I made a Halfling PC who went Monk 4/Rogue 6 and found that to be all kinds of awesome. I made him a "mage-slayer". I loaded up with as much movement-improving gear and feats that I could and my role was to break through the front ranks and go after any casters. This usually put me within stiking distance of 'bosses', but with the joys of high saves and evasion, it usually didn't matter.
As an aside, I made a Halfling PC who went Monk 4/Rogue 6 and found that to be all kinds of awesome. I made him a "mage-slayer". I loaded up with as much movement-improving gear and feats that I could and my role was to break through the front ranks and go after any casters. This usually put me within stiking distance of 'bosses', but with the joys of high saves and evasion, it usually didn't matter.