This is part of what I wrote on another thread the other day about RUSH.
first off, are you a student? If so... bring your ID to every box office you're trying to get RUSH tickets for. it's an absolute must.
Color Purple - just camp out. If you get there around 8 (2 hours before the box office opens) you'll probably be 10th - 12th in line. I think they sell 20 rush tickets, maybe someone can confirm that though. So i'd suggest NO LATER than 8:30am to get to the box office for that.
Jersey Boys - for an 8pm show, they sell student tickets for $25 from 4:30-5:30 only. People get in line around 2:30/3:00ish for those. And they are basically gone about 5 minutes after they go on sale. So plan on getting in line no later than 2:30 for those and just waiting out the two hours. There's a starbucks right down the street so it's not so bad.
RENT - I'm i'm not mistaken, they do have student rush tickets certain days of the week. I think Monday, Tues, Thurs. Where if they are not sold out, they'll sell you two tickets per ID for a reduced price. I think $40 a ticket. I've done this before. I got right orch seats aisle K. But if not - go for the lottery. Bring people to help. You never know how that lottery will be. I've gone days where everyone wins, and days where there are so many people they can't all fit on the sidewalk. But really, its tourist time and so you'd better just assume it'll be packed. Don't ever assume anything is a sure thing.
light in the piazza - DEFINITELY sign up for lct student tickets program. you sign up online, and you can purchase (in advance) a single $20 student ticket. Now when you pick up the ticket you have to have your student ID, but its a sweet deal. For a while they weren't doing student tickets for Piazza, but they might have started it again now that sales are a bit low and it'll be closing soon. Here's the site...
http://www.lct.org/studentix/ sweeney todd - if you go to the box office day of the show, they'll sell partial view tickets for half price. I don't remember if they asked me for my student ID or not. It's worth a shot, I don't think they sell out shows, and these seats are usually available.
doubt - 2 hours before curtain, 2 tickets per ID (despite what the talkinbroadway site says... i've done this twice already) and they're $26.25 or something like that.
If you have time, you should add into your itinerary Drowsy Chaperone. Or if you haven't seen it yet. HIGHLY recommend it. And they have a lottery an hour before curtain (get there an hour and a half before the show... tuesdays are 8pm, just fyi...) for $25 lotto tickets. Or if they're available rear mezz (still great seats) go for $25 as well. good luck!
This site is very informative too if you are curious about other shows rush policies.
http://www.talkinbroadway.com/boards/