I sat in Rear Mezz A for In the Heights and I agree that the view from there is perfectly fine, especially if you're looking to save some money.
I also agree that Follies is a must-see. And War Horse is nothing short of stunning. I'd go with those two if you're able. I think War Horse also just released a Broadwaybox could, but I could be wrong. In any case, that one's worth a splurge.
In terms of Book of Mormon, there's lots of detailed information about lotto and related things on the board, but, in essence, hundreds of people enter the lotto each day and it's very tough to win. If you're willing to wait all day, you can get in line for standing room, which is a much easier bet if you get there earlier and it's a great value. $27 at the back of the orchestra...I did it and it's so worth it.
"Art, in itself, is an attempt to bring order out of chaos."-Stephen Sondheim