In a PG I really like speed and BH. If you can get a great combo of ath, speed, and BH, that's even better.
You mention LP in guards and whether it's necessary, it's definitely necessary in my offense. My SG has decent ath, very good speed, and great LP for a guard and he's about to score his 1000th point in his junior season. I have another SG who has a good shot at getting 1000 points without ever starting a game in his career, because he shoots 50% from 3. I bring him off the bench to punish other coaches if they go to a sagging defense. He's not great at anything other than PER, so having a great PER rating can certainly make someone an offensive threat in the right situation.
SF(in my offense) is very similar to SG. I would trade some of the speed for rebounding, which is the case if you look at my SG and SF.