I did this in 2010 and well worth it. Had two guides (one was a past CM on the GMR, the other used to be involved in direction if parades. Both had different number of years experience)
We started in Epcot and went backstage at WS. Saw how the show at the American pavilion worked. Met some of the workers and they spoke as well about the show and there time at Disney. Got to see the workshop/repair shop, had a walk along main st in MK and in the utilidoors (saw the pin trading room for CMs bit weren't allowed to trade) got some info as well about the windows on main st. Saw how tower of terror worked and got to see the costuming work shop on DHS. Saw the tree nursery and the preparing the topiaries then headed to AK were we saw the prepping the parade floats. The younger of the tour guides used to be the director for MJJP (not sure if that's the right title for her) so she was real informative. Got up close to the parade floats. Then we got a fantastic spot for the AK parade which resulted in the characters giving us extra attention as we were with Disney institute people (that's who runs the tours) also had lunch at whispering canyon which was yum. During the tour we heard lots of stories from the CMs and got to speak with loads of CMs backstage.
I would love to do it again and would definitely recommend doing it. I think when you do the tour it makes you much more aware of all the detail that goes into the parks, rides and costuming. Certainly well worth the dollars and a must for anyone who wants to know more about Disney and how it operates.
Dont want to give away too much information to spoil it for any possible tourers

We did the BSM tour in September 2009, before they included the Animal Kingdom aspect!

We all met at Epcot - then it was off in our Coach for the back stage magic tour - which has lovely cold bottles of water on board.

Our first stop was American Adventure, where you go behind the scenes to see how this works. Then out front to look at American Adventure from the front and have a number of interesting facts pointed out to you.

Next stop was DHS - backstage to Tower of Terror and Rock n Roller Coaster, and a bathroom stop.

Next stop was costume department to see the different processes for costumes, and how they are assembled. A lot of interesting facts were divulged during this time, some very interesting. We actually saw a dress being made which was worn by Demi Lovato in Sonny with a Chance!

We also visited the laundry department - which is highly automated but very very interesting.

Another visit was to the Disney Nursery's where we saw the banana plants for the elephants at AK. Also saw the figures used around the parks during the "Garden Festival". We have some lovely photos of the different characters here - you were allowed to take pictures here.

At MK we visited the utilidors and had a tour around them, then it was on stage for the afternoon parade. After the parade a trip up Main Street to look at the various windows. This part was very informative and interesting and you will notice things you will never have noticed before. This is actually true of the whole tour. We found it to be very informative and interesting and in our opinion actually makes you appreciate Disney and what it stands for even more.

Then back on the coach to be dropped off at Epcot and receive your goodies. The backstage magic tour pins.

As previously mention there is also the lunch at Whispering Canyon Cafe - which was absolutely lovely. They happily cater for any allergies - I have a milk intolerance and they brought out a seperate pallet of food for me which didn't have butter used to cook with. My mum is seriously allergic to strawberries and had a special desert brought out for her, and one cooked without butter etc for me.