Rogue dips?

[Herobizkit]

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.

[StreamOfTheSky]

I disagree. With the books the OP listed, I'm not convinced there are enough feats to make Fighter 2 worth it, unless the game is going to end before you reach the double digits in level.

(Note, the following is based upon the OP saying UA content from d20srd is allowed)

I think if you're not going full Rogue, the best thing to do would be 1-2 levels of Barbarian. It gives better HD and skills than a Fighter; same BAB, saves, and weapons, and worse armor (but you're gonna wear light anyway). After that, you're basically trading 2 Fighter feats for Rage, Fast Movement, and Uncanny Dodge, all useful to a Rogue on their own. But then, there are variants to use for more flexibility.

Rage is useful for a sudden boost in combat prowess and hp/fort saves. But I think Whirling Frenzy is even better. More AC, chance to flurry (extra attack on full attack, all suffering -2 to hit) any given round with any weapon you want (even ranged ones!)...definitely useful.

If you don't think Rage 1/day is useful, you can always swap it away for a favored enemy and Rapid Shot.

Uncanny Dodge at Barb 2 means you get Impoved at Rogue 4, earlier than normal. If you'd rather just wait till Rogue 8, you could be a Wolf Totem Barbarian. That would give you Improved Trip, without needing the prerequisites.

The other Totems might be worth looking into, Wolf is just my favorite (from UA). Barbarian also lets you pick up some nature skills, though Wilderness Rogue variant also allows access to them.

[Darklone]

Agreeing with StreamofSky. 2 levels barbarian are great for charging and spring attacking rogues. Uncanny Dodge Synergy is great and you make up for the loss of sneak attack damage by taking a twohanded weapon, Power Attack and Cleave. Reach weapons are nice for this build too.

If you go Fighter, take 4 levels: think about a heavy armored TWF dwarf tank. Doubleweapons are great, you have the feats to use them and can change between flanking sneak attack devastation or twohanded weapon Power Attack goodness. And you'll reach BAB +16 for 4 attacks at level 20.

If you go wizard, you'll enjoy INT synergy (rog/sor are only good for facemen with high Cha and less Int), three levels will give you as many useful spells as you can buy (true strike, mage armor, shield, invisibility and maaaaany others that stay useful at higher levels, blur, blink etc...), no problems with most magic items, and a good reason to stay in the backrows in fights. Cheap wands are your friend.

[insanogeddon]

Beguilers with a breath weapon.

Rogue 1, Rangers 19 (search is a class skill)

Rogue, Swashbucklers with 'Daring Outlaw' if that is allowed from C.Scoundrel.

Rogue/Barbarian. Barbarian gives faster moving for escapes, needed hit points, massive damage for the crit/sneak immune, stacks uncanny dodge so you cannot be flanked or sneak attacked by jealous guild assasins, survival (you may as well have track as the point man.. very handy), and rage is a great role playing supprise and punishment for those who see you hiding.. 'you saw me? that makes me ANGRY'

As a melle channel: Rogue 4, Barb 2, Pious Templar 10 nets you rage/2d6 sneak attack and specialisation (thus mastery), spells, good DR, EVASION AND METTLE !