I would agree with Iron Horseman and strongly suggest if you have used Snap Switches, not to. They have plastic frogs (or, at least they did when I used them) in addition to that fact, they have very tight radius, per Iron Horseman's reasons. The plastic frogs may not be an issue; but, the possibility exists that you might eventually wish you had used metal frogs so they could be electrified. You have also built in two reversing loops into the layout you show. You will need to learn how to wire them. Are you going to run DC or DCC? What era do you have an interest in?