Trains, trains and more trains.  We invested in this wooden train set when Lexie was 18 months old.  I am so glad that we did, it has lasted FOREVER and still seems brand new although it has been played with by our three children and countless cousins.  We had added pieces throughout the years but the base set is still there.  We also have a huge set of plastic tracks that hold smaller trains that are also a family favorite, in fact what you can't see in this picture is that the rest of my family room floor is covered with the other set of tracks.  Lexie was the master builder today and the kids played for hours.