Kristen~
I have some ideas for you that I have done on trips with Youth Groups in the past:
1. Keep a "log" - I did this on a cross-country road trip with a group of friends and it was really fun! Basically, have a small notebook and pen with you at all times and when something magical/humorous/memorable happens someone in your group writes it down. We wrote down funny quotes people said, embarrassing moments (that you want documented), etc. and it was really cool. We have this book with everyone's handwriting and all of our experiences in one place. I think the age of your kids would be perfect for this activity (you might need someone to help get it started, though).
2. Amazing Race - This will take some knowledge of the parks and some advance work, but it could be kind of fun. And there are a few different ways you could make it work. Like the show, you can have Challenges that the group has to complete (in groups or individually). These challenges can be as simple or as elaborate as you want. When I did this with a group last Fall, they had large challenges to complete for big points, such as games, relays, etc. Then there were small challenges for fewer points such as photo scavenger hunts, a list of items to collect, etc. I think you could easily do this at Disneyland with a few modifications. You could plan an elaborate day of challenges, but I think you could also do something simpler. Maybe say "the first person to find a hidden Mickey wins" as you are touring. And for the "prize" they could chose what you are doing next, etc.
3. Mind Games in lines - This is always fun with teenagers, and I am sure you can find a lot of games like this online. One fun one that gets really funny is to eliminate a word for an hour or two, such as "ride" or "Disney" or something. Then if you get caught you have to do something mildly embarrassing or be silent for 5 minutes.
These aren't necessarily Disneyland tips, but I hope they give you some ideas! Have fun!