I don't think anyone has recommended High 5 yet.
http://www.highfivetix.org/splash.aspx
They sell discount tickets to museums, concerts, plays (not broadway) to teens and to their parents. Sign up for their newsletter.
This summer my two Ds visited the Gugenheim for $7.50 total. The regular price, with student tickets would have been $39 as I recall. But the High 5 museum tickets are 2 for $5, plus they let a parent tag along. Just be sure she brings a student ID.
When you're buying Broadway tickets, remember that Broadway theatres are much smaller than some of the huge venues in which the rest of us are forced to see traveling shows. The "cheap seats" in a Broadway theatre are so much closer to the stage than the cheap seats at my local larger theatre.
So don't feel like you have to splurge for the "best seats in the house." High up, but center, is fine.
Has anyone recommended
In the Heights? It's WAY COOL.
I love broadwaybox.com.