Hi Jo Ann! I love that you and your husband are planning a trip to Disney World just the two of you! I would definitely try to take in
Epcot's Candlelight Processional. It's a lovely performance, where you can listen to a celebrity special guest read the Christmas story, accompanied by a 50 piece orchestra and choir. After, you can enjoy a lovely dinner in one of international restaurants, and then view the spectacular IllumiNations. A perfect evening!
Mickey's Very Merry Christmas Party at the Magic Kingdom is a fun, special ticket, event. You would definitely enjoy yourselves even without kids, although I might be tempted to put the ticket money towards a lovely dinner at a signature restaurant. The Contemporary Resort's California Grill is awesome, and located on top of the resort, offers up the best views of the Magic Kingdom's fireworks. The Flying Fish on the Boardwalk is another favourite of mine, and you can enjoy the entertainment of the Boardwalk after your dinner.
I hops this helps Jo Ann! Write back if you have any other questions!