I like the spread plus or minus points idea but we are going to have a lot of players who aren't really familiar with the sport so I don't want to make it too complex for them. But I do like the idea that some picks could be worth more than others.

When I did the MLB playoff point challenge I just made each round worth increasingly more and added a bonus to each round (in that case was the number of games a series would go, but maybe in this case would be related to point differential).