Question; do you have the ability to hoist it up to the ceiling of the garage on pullies with a manual or electric winch? If ya do, you could go larger. Bring it down when you wanna play with it, crank it up when you are done.
Another option if you don't want the layout always up and running would be to build a layout using the Lionel Modular Layout sections. Take them out when you wanna run trains, put them away when done. This would give you easy access to the layout and allow for very wide curves.
Just a thought
