Not a huge point, but something else to mention is that Wis boosts your Will save (important!) and your perception skills. Cha boosts your social skills, which will vary in usefulness depending on the mood of your DM. Your perception skills will determine whether or not you get to act in the surprise round.
Granted, it's not that hard to boost your Will save, especially with one or two PrC dips, but a good Will save is vital to any PC.