You are right that people are taking the warnings more seriously because of Joplin. We used to sleep right through the watches, but the night after Joplin we were WIDE AWAKE during the ~hr long watch at 1:30 am. Our hallway that is the only interior "room" in the house, if you close all the doors, no longer seems quite adequate as a shelter.
The house we're moving into tomorrow has a basement. Unfortunately, this is also an area prone to floods, so basements aren't a great idea. I guess the ideal house for this area has one of those closets that doubles as a storm shelter, regardless of exterior or interior walls.

