We did the Behind the Seeds tour on our trip in September. We walked up at about 15 minutes before the tour and signed up. We got a discount using our Disney Visa, and I think they offer a AAA discount too (not combinable). It lasts about an hour and was fairly cheap. With our discount, I think we paid under $25 bucks for the two of us.
My partner is very into gardening and the idea of hydroponics, and he really enjoyed the tour and getting to see the different methods of growing, as well as getting some great pictures.
I haven't the slightest interest in gardening or hydroponics, but I still enjoyed the tour. Our tour guide kept it interesting, and I admit, I had fun learning about the processes.
It is amusing seeing the people on Living with the Land gawking at you as they pass by on the ride. I wonder how many people's photos we ended up in during that hour.
Definetely ride Living with the Land before you take the tour... this will give you a layout of the greenhouses, and if you think of any questions, you can ask them on the tour.
We didn't take the other two tours you asked about. We did take the Keys to the Kingdom Tour in Magic Kingdom, and really enjoyed that one as well.
If you haven't, check out
www.allears.net, and look under the Rate & Review section. They have some more current reviews on several tours.
Have fun!