Rogue/Assassin build...

[V'rass]

Going to try a 10 Rogue/10 Assassin/ 10 something else...

May or may not work but it will be fun to test at least.

[Blackman D]

you probably only want to go 9 assassin, its the last level that gives a damage dice

depending on the something else you can go up to 8 something which will give you 13 rogue for an extra feat

[Thorsson]

Ro10/Asn10/Duelist10 or replace Duelist with WOD or Dervish; Ro13/F8/Asn9; Ro10/Asn10/SB5/IB5 (or replace either with Te5).

[freekender]

A classic build that works fine is R 16 / Ass 9 / IB 5. This way you can get Epic dodge and Epic precision. And being a monkey skill rogue is always fine

EDIT: You could go R 10 / Ass 9 / WD 8 / ? 3 and still get both. Those epic feats are must or nearly a must.

EDIT2: The correct split would be R 13 / Ass 9 / WD 8. Whirling Dervish doesn't get Improved Evasion at lvl2 here. Another posibility could be R 13 / Monk 9 / Ass 8, but this is further from the R 10 / Ass 10 / ... split you originally posted.

[Deathgrowl]

Rogue13/Fighter8/assassin9?

Rogue10/monk11/assassin9 with kama flurry?

Rogue13/assassin9/wilderness stalker8? Camouflage!

[Thorsson]

Rogue13/Fighter8/assassin9?

Said that.

Rogue10/monk11/assassin9 with kama flurry?

Although it would miss out on Greater Flurry, I'd prefer Ro13/Mo9/Asn8 to get both Epic Precision and Epic Dodge.

Rogue13/assassin9/wilderness stalker8? Camouflage!

Not keen on this. Monk gives you speed all the time and better things than Camouflage.

As you can't get EP & ED you'd be better off anyway with Ro10/Ra3 IMO - a FE, free Track, TWF & Toughness and +1BAB. OK gives up 2d6 SA, but you're not struggling for damage anyway.

[Deathgrowl]

I prefer dropping assassin altogether.

monk11/rogue16/sd3

rogue17/sd3/wilderness stalker10 or other variants.

Rogue19/fighter8/sd3

Loses death attack, though.

[Thorsson]

Loses death attack, though.

Which is a pretty big (invisible) BUT.