I'd take a chance with Okafor. God knows they need some length and scoring up front to complement Horford. He's a kid with upside that needs coaching. He also needs to get away from a bad situation in Philly where they have too many 5s. Guys that can't play the 4. Horford can play the 4. In fact, it's said he prefers the 4.
So what are they waiting for? I think they've made Griffin a higher priority. They are also waiting for Okafor's price to come down. They don't want to give up the Nets picks--I guess. Making Griffin a priority isn't a money thing. Okafor is cheap and protected. Maybe it's players, or maybe the draft picks.
If there is no conflict with what it would take to get Griffin, I'd get Okafor right now. He's better than Zeller and cheaper. And he has upside. They have to improve their bigs, and they are running out of options.