I haven't done Keys but can give a little input into two others........
In October 2003, I did the Hidden Treasures of the World Showcase tour. I'm a huge fan of the WS and could truly spend my entire vacation there (but don't) so this was a must for me. Our group met up outside of Guest Services at Epcot around 8:45 a.m. and walked through FW. We did make a couple stops there for our wonderful guide to give us some inside info. Then we made our way to WS.......WS was not open yet for the day so it was very nice to see the pavilions without many people. We took our time and our guide told us great details about each pavilion and allowed us to take pictures when we were "on stage" (we went behind the scenes briefly and no pics were allowed there). WS had opened by the time we made it all the way around but there were still so few people that it was not bad. I would highly recommend the tour as I learned an abundence of info that I didn't know about before. Trust me, you'll look at the pavilions in a completely different way once you take the tour. Our guide was wonderful and insightful and the day was just perfect. There is a lot of walking and standing involved so keep that in mind.
In October of 2004, I took the Backstage Magic tour. What an amazing tour this is. Again, we started outside of Guest Services at Epcot just before 9:00. We walked as a group (in both tour cases, the groups were small) into the park and then immediately went "backstage" to a
Disney Cruise Line bus that would be our "home" for the day. This was cool because the bus was very comfortable and big for the amount of people we had and they also kept water in a cooler on hand. We had 2 bus drivers who drove us around and stayed with the bus while we were out in case we wanted to leave anything on board. I won't divulge too much about what you do but we went into many backstage areas at Epcot, checked out the wardrobe department and saw the workings of the American Adventure show. Our fabulous guide gave us lots of info on other Epcot tidbits as well. We then went to the Disney Flower Shop and toured this building. Fabulous. After that, we hopped back on the bus and went to Disney Studios where we went to the huge costuming center where they make many of the costumes for the parks. It was wonderful. We stayed backstage for a bit and then did lunch at Mama Melrose's -- this was a highlight as the meal is family style. They brought out many different appetizers, entrees, desserts and we all tried each. After this filling meal, it was back on the bus and behind the MK we went........to the gigantic building that houses the Christmas decorations and to a huge metal shop where many different ride parts were being serviced. We ended our day at the MK, where we did a visit to the utilidors (very cool) and went into the park for some inside info. Our last thing........we walked down the blocked off street just before the parade (learning cool things on the way) and then guided to the very end of the route to watch the parade. The bus parked behind the scenes at every park so we had easy access. As we were leaving, our guide asked who was staying at a MK resort so me (at CR) and another couple were dropped off at our resorts. The others were took back to Epcot. Notes for this tour -- it's fabulous and a must do in my opinion...while there is a lot of walking and standing, there is also good rest time (you're on this tour for 7 - 8 hours).....I was very tired by the end though.
It does help to have a great guide and I was lucky to have wonderful guides on both tours. Which would I do again --- BOTH! If I had a day to spare, I would likely do Backstage Magic again but since most of my trips are tight on time, I will probably do Hidden Treasures again....................or maybe do a different one!
ANOTHER NOTE....while I haven't done the AK Safari tour, my mom and sister both have and LOVED it.