If you (a) can afford it and (b) are in New York all the time, seeing previews is perhaps one of the best ways to learn about the process of creating a musical.
I wasn't able to get to the out-of-town tryouts for Legally Blonde, which, save for "Wicked" is probably the best-represented show on Youtube.
I have to say, watching the San Francisco footage and comparing it to the MTV show, or any other footage shot at the Palace is like a master class in directing.
The show was clearly on its feet in San Francisco, but the amazing amount of detail work that was done prior to the Broadway opening is amazing.
I love previewing (and besides, as in the case ofthose lucky enough to see "Carrie" and a few other shows, that may be all you'll get.
http://www.broadwayworld.com/board/readmessage.cfm?thread=972787#3631451
http://www.broadwayworld.com/board/readmessage.cfm?thread=963561#3533883
http://www.broadwayworld.com/board/readmessage.cfm?thread=955158#3440952
http://www.broadwayworld.com/board/readmessage.cfm?thread=954269#3427915
http://www.broadwayworld.com/board/readmessage.cfm?thread=955012#3441622
http://www.broadwayworld.com/board/readmessage.cfm?thread=954344#3428699