The evening was filled with special activities and programs. We were the first to see their newest exhibit on whales. It was fun just to be one of 100 or so people roaming the museum until midnight. We ended up sleeping in the nature's mystery exhibit under some trees. [People brought inflatable beds. I brought a camping bed roll which worked out fine.] I can't promise you'll get a lot of sleep.
The next morning, after breakfast, we wandered the museum some more before the doors opened to the public. We saw a fantastic Omni movie on whales and purchased some souvenirs at the museum store before heading home.
This was truly a child's dream come true (even at my age). Whether you are a parent, grandparent, aunt or uncle, I highly recommend looking into what your local museums have to offer. If they have overnight programs, it is worth doing with your favorite kid(s). It will be something you always remember.