"What if" is fascinating and funny, science and mathy, though much of the "what ifs" don't end well for mankind. But usually in a funny way unless DS is very fearful. The reader (Wil Wheaton I think) is a big part of why it's a good listen.

I hear Wesley the Owl, and Grayson, are good reads. They are on our list but haven't gotten there yet.

We also enjoy NPR's "Driveway Moments" and "Fresh Air with Terry Gross" for lighter fare.