I think our backcourt is set if we can get West, Daniels and Green back (not a given, but certainly not unrealistic).
I think there are a number of ways we can build a contending frontcourt.
Kenyon Martin would give us great defensive speed and versatility (a great boon against Miami, OKC, NY and Chicago), but probably at the expense of letting KG or Kenyon getting beat up by the occasional big 5 (Bogut, Marc Gasol, Howard, Bynum). He's also not the paragon of health.
By contrast, Joel Przybilla would make us extra big, but potentially more vulnerable to the speedier teams. And he's even more of health risk. Still, Garnett, Joel P., JO and Jeff Green is a championship caliber frontcourt if healthy come playoff time. I'd put Jeff Foster on Przybilla's level of impact as well (different players and skillsets, but similar value/risk/impact).
Chuck Hayes is my favorite option, as he has a clean bill of health and he'd fit in nicely with all of our other big man options: with KG or Jeff Green, he'd take the bigger post-up threat and crash the offensive boards; with JO, he'd take the quicker frontcourt guy on D or the post-up guy to free up JO's weakside shotblocking, and operate out of the high post on O (he's developed into a very nice passer). He'd be a souped-up Big Baby without the J but with much better rebounding, defense and decision making. I'm just crossing my fingers in hopes that Houston lets him go (with Thabeet, Miller, Hill, Scola, Patterson and lottery pick Marcus Morris all on board for next year, and cap space precious for 2012, there's at least a chance).
Kwame Brown could do a poor man's Perk routine for us, but I don't think he offers enough to be the main plug for our big man rotation.