I did this tour last summer and it was well worth it. We did get the AP or DVC discount (which ever was better).
There was a bit of walking, but there were some older Disney guests that were on the trip and for the most part... they did ok (a lot of stopping in between.)
We were able to see the x-mas decoration storage facility (they work year-round to get ready for the next season), the disney florist, the american pavillion in epcot, underground utilidors at MK, a great lunch at Mama Melrose's in MGM.
There were so many interesting things that we learned, it was well worth the price.