One Christmas, when the girls were around 8 and 5, N and I were scratching our heads over how to wrap their last big gifts (matching child size sleeping bags). I don't know who had the treasure hunt idea first, but we both agreed it was the perfect solution.
The two of us began brainstorming and came up with 5-7 riddle type clues to hide around the house. We put the first clue in an envelope addressed to both of them on the Christmas tree in plain sight. Round about 6 AM (maybe earlier) two excited, pajama clad girls made waves when they plunked themselves on our waterbed and patiently waited for one of us to show signs of life.
We feigned sleepy surprise while listening to what they'd found and what the note said. Their eyes were big as they launched off the bed in search of the next clue and the whole scenario was repeated over and over until the treasure was found--in the dryer.
At the end of the search, we realized we hadn't bought ourselves any extra sleep, but we had injected a little more excitement into the day. It became a yearly ritual until we forgot one year and never began again.