1. KTTK - As other have stated, a long tour with lots of walking, but very interesting, plenty of behind the scenes and insider information, and includes a sit down lunch and a trading quality pin . Dh and I did this a couple of years ago and really enjoyed it.
2. AK behind the scenes tour - We did this 2 years a go and it was NOT walking based at all! We met up by the front gates and moved from place to place in vans. We visited the kitchens, the vet clinic/animal case facilities, had some classroom time with an animal handler and an animal (our was a lizard). We went to the elephant house, but did not go inside. We DID get to PET the rhino, which was just about the coolest thing ever. My mom and siter did this tour one year later (last year) and did NOT see a rhino. He was being released back into the wild, so maybe that is why. Got an AK trading pin. I would still recommend this tour, even without the rhino.
3. Seed tour at the Land in Epcot - Did this 2 years a go. Its a shorter and much less expensive tour - tickets can be purchased day of at the Land. The interns actually run this tour, which I thought added to the experience over all. We learned about the planting techniques and natural pest control, got to try the cucumbers, and were stared at with envy by every boat that was going through the ride! We also got to see the baby
crocs (or alligators - can't remember) and feed the fish. Definitely worth the $12.
4. Epcot Aqua Seas Tour - Did this last year and LOVED it. Included a tour of the facilities, a safety video/speech, then some quality time squishing ourselves into wetsuits! They let you choose whether to walk to the tank behind the scenes or right through the main exhibit area - through the crowds it was for our group! You get tanks and a regulator, but no weights, so while the breathing is like scuba you are limited to trolling along the surface. Everyone looking in the tanks can see you and it was fun waving to the kids! The sea turtles can be curious and one surfaced inches from my husband!!! We got at least 30 minutes of tank time - it felt like a long time - not rushed at all. We got t-shirts and souveneer photos of us in our gear in the tank. (And a cheesy round pin - not a trading pin, for those who are into this kind of thing.) Two thumbs up for this one.