Just to add to Logik's post, API is a great indicator but the other things they mention are also important.
Just as an FYI, we have one kid in a high API school and one kid in a lower one. While we aren't very happy with the low API school, the teacher is great and our child thoroughly enjoys the class so we've kept them there. As for the high API school, we do notice the difference school-wide when compared to the other school and the teacher is good too, but a little more strict when it comes to grades.
We've also toured "reputable" schools with high APIs but got a bad vibe from their staff so we ruled them out even though our friends highly recommended them.
So like I said, it's very subjective and wherever you decide to land, just make sure you put the time into it to help smooth out the bumps.
As for your 'hood choices, older and newer have pros and cons. Newer has the advantage that many of your neighbors will be families and have kids the same ages as yours, but older will have the advantage of an established school and staff.
But, you will notice a trend that the newest schools get the highest marks but that may have a chicken-egg effect as the parents are more involved since they've "invested" so much into their home and neighborhood.