The chemistry and solid state physics of the actinides is pretty interesting because of all the electrons whizzing around: consider the infrared spectrum of thoria which makes it the choice for gas light mantles or the glow in the dark behavior of uranium glass which has nothing to do with radioactivity.
Not forgetting the Lanthanides, their cousins in the f-block, which have various interesting optical / catalytic / magnetic properties (e.g. Europium, Cerium, Neodymium).