Amatos in Middletown has a ton of Lionel. They have two rows dedicated to O gauge. Most of their stuff is Lionel to inlcude a ton of Fastrack and, O-31 and O-27. One how side of a row is nothing but stacks of rolling stock (Lionel, MTH, ATLAS, etc...). About two entire sides are nothing but accessories and buildings. A whole lot of RTR sets as well.
They have a decent amount of engines too that are all on display. Being in CT they have a lot of NH but also a lot of other flags as well.
Aside from O they have two rows dedicated to HO and N. They have LGB stuff as well. There is a whole row that is nothing but Woodland scenics and other scenery stuff. They also have all the Lionel books and magazines and the latest pricing guides.
If you have kids bring them. They are also a serious toy store and are a great place to find those items that are not going to be found in any Toys-R-Us.
I live about 45 minutes away and its always a treat to go there.