I think that the 'follow the string' game or treasure hunt would be great!
What a great gift!! I had been driving a very old Volvo for years and years and years. It had no heat which meant no defroster. Lol!! I had to keep pouring cold water on my side of the windshield, as I was driving, to be able to see in the winter time!! Oh gosh...memories. Anyway, hubby gifted me with a truck and I was totally blown away and astonished and so so so happy!!!!
Your wife will adore you and love your thoughtfulness!! What a happy Christmas at your house!! Way to go!!!