DH and I have taken the unDISCOVERed Future World tour and thought it was awesome. On our particular tour, we got a lot of history of the park and design details (including a lot of explanation of how The Land pavilion was designed - which was awesome), visited the VIP lounge at The Seas, saw the 3D glasses cleaning area, skipped to the front of the line on Soarin, and went to Cast Member Services. It was really a great tour and I would highly recommend it if you love Epcot.
My dad and stepmom took the WS Destinations tour last fall and loved it. My dad said it made him see so much more detail of Epcot that he wants to go back and explore more and take more tours.