While searching through Google, I remember a number of pet blogs talking about the "International Box Day". They would have pictures of their pets hiding, curling, and lying inside boxes like this...
Yes! They both are absolutely intrigued by boxes. We got a package in the mail and we now put it on top of their bed because they love sitting on top of the cardboard box. Without it, they'd ignore the bed. We had another box and Max, our oldest cat, just sat in it and watched us (maybe he thought he was invisible?)
That is an adorable picture. My cat loves boxes and hiding in cabinets, and small dark spaces in general.
Apparently the expensive pet catalogs know that cats love boxes because I saw what was basically an overpriced cardboard box with designs on it for sale in a high end cat catalog.
My older cat is not really a lap cat. But I have one strategy that often works. I bring home a new cardboard box. After she has settled into it and gone to sleep, I gently pick the box up with her still in it, and put it on my lap. It helps. She does actually stay for awhile, until she realizes that she has to maintain her image as a non-lap cat, then she hops down.