Hi, Kelsey!
There is so much to do at Walt Disney World, and everyone joins in the fun so I don't think you have to worry about feeling that anything is too "young!" (Just wait until you see how many adults are wearing their Mickey Mouse ears!)
For nighttime fun, you never even have to leave the parks! With Extra Magic Hours, parks are sometimes open past midnight. This is a great opportunity to enjoy the parks late into the night when the temperatures are cool and the crowds get smaller the later it gets.
If you are looking for something outside the parks, head to Downtown Disney. You can enjoy a balloon ride 400 feet over Village Lake on Characters in Flight. You might also want to get tickets to see
La Nouba. This Cirque du Soleil show is awesome! You can also catch dinner and a movie at the AMC Theaters.
Another nice adult option is dinner at the California Grill. Schedule a late dinner so you can see Wishes (fireworks) right from the restaurant! The views of the Magic Kingdom are amazing from this location at the top of the Contemporary Resort.
If a dinner show sounds fun, book a luau! The
Spirit of Aloha show is a lot of fun with great food and entertainment.
Whatever you decide to do in the evenings, I hope you have a great time!