Being a surprise doesnt mean you can't talk about it! My kids are just as obsessed with Disney as I am.
Disneyland comes up in our daily conversation- almost every day, if not multiple times a day! They talk about memories, what they want to do on the next trip, things they like to eat, etc. They watch the planning videos just for fun. They know there is almost always a trip in the works. It might not be for a year, but there is always one!