Did the Marceline tour last summer with our family--me, DH, DS14, and DS16. We all LOVED it. As others have said, it's a great length so it doesn't eat up a whole day but you still get to see and do so much.
We all love Haunted Mansion so that was a highlight. Without giving too much away, you're group will go on the ride together, with the guide in one of the middle doom buggies in the group. He's able to narrate so you can hear a lot about the details as you ride through. And then there's another amazing piece I won't go into at all!
We also got a private viewing of Carousel of Progress, again so he could point things out throughout.
We were told no pictures during anything backstage. He allowed us to take pictures in an empty Liberty Square, but told us if there was anything "out of place" we'd have to put cameras away.
Highly, highly recommend this tour!