I prefer to call it a display layout versus a hi-rail layout. What level of abstraction or realism is used to portray the layout.
I would say toy is a certain appearance used in both type layouts. Some of the nice tinplate layouts say toy to me and are display layouts.
Eddie's layout is a nice display layout designed more for running trains than prototypical operations with an abstract approach to the scenery. His town creates the illusion of a town, but without the exact representation of detail. I think most of us build that type. Check out some of TWTrainworx layouts.
The first element, to my eye, of a display layout is continuous running. Real railroads go out and come back, sometimes using wyes , turntables or balloons to turn a train around. They don't run in loops.
Any way, pardon my detour. I enjoy the art of a layout.
If it's track plans you are looking for, then look at any and all. The internet is great for that. Grades are pretty much the same in any scale. Anything over 2% is a steep grade. O Gauge Model trains, with traction tires or magnatraction can handle up to 4% grades, but they cause special operating adjustments. So, if you stay at 3% or under you should not have a problem.
Your table size limits you to 054 diameter curves for most track mfgs and 060 with FasTrack or smaller diameter, not counting easements. 4.5" to 6" center rail-to-center rail spacing will give you enough clearance for mainlines. You can get tighter in a yard.
Then decide on your track to scenery ratio. Even placing buildings and accessories can eat up some real estate. They are 4" x 6" and larger footprints. On a double loop with some switches and a stub or two, you can reduce the available places for buildings and accessories quickly on a 5 1/2 x 10.
I've attached a 1954 Lionel Manual that has 5 x 9 track plans, a very thoughtful article on the design your layout process (which I think will help you focus, easy read).
Thortrains is a fun, common sense place to start with a lot of examples of layouts and train related ideas and experience.
Unless you are choosing a specific section of a railroad in a specific time period, then you are right in there with most model railroaders. So, look around see what you like, call it what you like and build it. There aren't any rules except for gravity and electricity. They don't change.
Have fun!
