Trading for Gasol cost the Lakers Kwame Brown, Javaris Crittendon, two 1st round draft picks, a second round draft pick and rights to Marc Gasol (Pau Gasol's brother), plus one other player I forgot. Crittendon is a 6' 5", quicker version of Jordan Farmar and can potentially play defense like Trevor Ariza. Marc Gasol is a younger, bigger, stronger and heavier version of Pau with better defense and offense.
Lakers shouldn't have thrown in Marc Gasol 'cause he has the potential to be a real impact player with his size and skills. All he needed, had the Lakers kept the rights to him, would have been 2 or 3 years, if that, of seasoning in the NBA, learning from Kareem and he would be able to dominate games at the center and power forward positions at certain times.
Lakers should have offered Farmar instead of Crittendon because Farmar will always have trouble playing against bigger/stronger Deron Williams type guards. Crittendon is quick enough to take on smaller/faster guards and also has better ball handling skills than Farmar. From what I saw during the his time with the Lakers, Crittendon doesn't seem to get fazed playing on the road but instead becomes more aggressive unlike Farmar who at times goes into a s for extended stretches.
All the other NBA teams, I think the Bulls were one of them, interested in Gasol only dabbled with the idea of a trade. The Lakers were the only team that gave Memphis a serious offer.