Sitting at IMAX is about as close to the action as many of us (like me!) will ever get. Their gigantic movie screen and surround sound have allowed me to climb Mount Everest, fly a plane and delve into the intricacies of the human body.
The theater seats several hundred in comfy cushioned chairs which are very welcome if you've been walking around the Museum for the day. The only drawback I can see is the line to get in is generally very long, there is no place to sit and kids get very impatient. Once inside however, you might find it was worth the weight as you are transformed into another world for at least a little while.