Hi Marilyn!
The four
tours I'm familiar with at the Magic Kingdom are Mickey's Magical Milestones Tour, Family Magic Tour, Keys to the Kingdom, and The Magic Behind Our Steam Trains. Since you mentioned scavenger hunt, I'm assuming you are referring to the Family Magic Tour. That's a fun tour, but my opinion is it's for younger kids, maybe 8 or 9 at the oldest. Mickey's Magical Milestones Tour is also geared towards younger guests in my opinion.
Keys to the Kingdom is an awesome tour and I highly recommend it for anybody who wants to see the backstage area, including the world famous Utilidors service tunnels under the Magic Kingdom. Unfortunately you have to be at least 16 years old to participate.
If you or your daughters are interested in steam trains, you may enjoy The Magic Behind Our Steam Trains tour. The minimum age for this tour is 10. I did this tour last year and I really enjoyed it. The highlight was a train trip back to the roundhouse with an up-close look at a locomotive. It was filled with history about Walt Disney's love for trains.
Have a magical vacation!