Hi Lori. Thanks for your question. I don't really consider any of the moderate resorts at Walt Disney World to be overly childish. I think it will really depend on the type of theme you are most drawn to.
Disney's Coronado Springs Resort has a real southwest feel but can be busier due to the convention facilities,
Disney's Caribbean Beach Resort has a very laid-back, island vibe, but it is the largest of the moderates and very spread out. Disney's Port Orleans Resort has three distinct personalities;
French Quarter has a fun New Orleans theme,
Riverside has two sections - Alligator Bayou, with a rustic, deep-south flavour, and Magnolia Bend has a gone-with-the-wind feel. There are queen-sized beds in all moderate resorts. All of the moderate resorts, with the exception of French Quarter, have a large themed pool and smaller quiet pools. French Quarter just has the larger themed pool. Personally, my family loves the Port Orleans Riverside Resort staying in the Alligator Bayou section. We love the atmosphere, food court and the option of taking a boat to Downtown Disney.
I know it's so hard to know if you're making the right choice in accommodations, but I promise you that any of these choices will contribute to your family having a magical Walt Disney World vacation. So check out the links, take a family vote, and start looking forward to your trip! I would be happy to help you with any other questions you have while planning - thanks for visiting the Disney Parks Moms Panel!
Kristen