We will be going to WDW in December with an 8 year old, 6 year old, and 8 month old. Is this tour manageable with a baby (who will obviously be in a stroller)?
It should be fine-- we didn't go into any places where you couldn't take the stroller-- there is some hopping and skipping -- but they will slow down and wait for you and the stroller to catch up. (And also to read the map and get ready to figure out where we are going next.)
Is this something a 12 year old would enjoy or is it geared more towards the younger children? How long does it take?
it depends on how willing your 12 year old is to look silly among strangers-- the 12 year old might find it a bit "dorky"-- I think it is geared maybe more toward the 10 and younger-- but I have read that adults only have taken the tour and liked it.
It is 2 hours long-- with a sit and drink break built in for about 10 minutes or so.
Diane