When we were at Legoland (great place for small children, by the way), my parents told my son he could pick out a set of Lego's. He decided upon a train set as he really likes his "choo-choo's". It was a toss-up between a Thomas train set and the non-Thomas set, and we decided on the non-Thomas one.
What a great decision we made! His cousin ended up with the Thomas one, and they said that there wasn't much to the set, for the same price they got the train and some track. We, on the other hand, got a battery powered engine, a train car, track with the center piece to make it cross over itself, pieces to build a train station complete with train station clock and waiting chairs, two train signal lights, a gas pump that really makes noises when you put it in the train gas tank, a conductor, a lady passenger, her purse, flowers and bushes, a cow, a hay bale (yellow lego) and a trough to put it in.
The only disappointing thing about this set is that it could have used more track, and it didn't have any straight pieces at all, so we did end up buying additional track, but other than that this is the best Lego set we have bought yet! It keeps my two-year-old entertained for hours, he loves putting the track together and starting up the train. He has a slight problem stopping the train without knocking it off the track, but he's getting better with that too. The train even has an automatic shutoff after two minutes so the batteries don't wear out!
Since it's Lego/Duplo, it's also compatible with all his other blocks, which is great for building massive cities with other Lego sets.