Has anyone mentioned a "monster" variant?
2fighter/18 ranger. Nets you +1 strength via fighter enhancement, fighter haste boost, class toughness enhancement, and 2 feats (plus a smattering of hitpoints from fighter's higher base). You do however lose you monk benefits and UMD from rogue. This also lets you hit a round 20 BaB, which i believe also means a small attack speed increase at cap.
Toss on rogue dillentante and 6 AP later you have an extra 3d6 sneak attack, and i say you have a pretty mean Half elf tempest machine.