Hi Alicia,
It sounds like you are going to take a wonderful trip! I do enjoy going to Walt Disney World with friends and family of all ages. Cirque du Soleil - La Nouba is a wonderful show; however, I do understand that it would get quite expensive for a large group. Let me make a couple of other suggestions.
You might consider a
specialty cruise. On some of these cruises, you can see either Wishes at the Magic Kingdom or Illuminations at Epcot. When you book a fireworks cruise, you book the boat for a flat fee and can then have up to a maximum number of guests, which, depending on the boat, is typically eight to ten guests. For more information about these cruises, you can visit the unofficial site wdwinfo.com. Once you are there, search "fireworks cruise." To book a fireworks cruise, call 407-WDW-PLAY (407-939-7529). Please note that fireworks are not guaranteed on these cruises as upon rare occasions the fireworks may be cancelled.
Another option that would be fun for all ages is to go to
Hoop Dee Doo Musical Revue at Disney's Fort Wilderness Resort and Campground. This is a fun show including upbeat music and dance which I think would be enjoyed by guests of all ages. It is not inexpensive; however, with this entertainment you are also getting a delicious dinner including some great fried chicken! You can book this show online using the link above, or by calling 407-WDW-DINE (407-939-3463).
I hope that this gives you some ideas for a special night on your trip, Alicia! Please do not hesitate to ask if you have any further questions.