Actually there is nothing wrong with 4x8 layouts. Even in HO you can fit in a decent amount of scenery and track, and they give you something a lot of shelf layouts don't - continuous running. Start with something simple like the Alkali Central to get experience. You can always incorporate it into a larger layout as a peninsula if you decide to expand later. I do think 4x8 is about the upper limit I'd consider for a table layout though. Anything wider and the reach to the center is too long.
I respectfully would suggest that there is indeed something "wrong" (or more correctly - something suboptimal) with 4x8 foot layouts.
if one wants to start with a continuous run layout on a table, a far better (in my opinion) option than a 4x8 foot H0 scale layout would be an N scale layout on a 30" x 80" hollow core door, for these reasons:
1) 30" x 80" in N scale is the equivalent of 4 1/2 x 12 feet in H0 scale - which means that you can fit more railroading and more scenery into less space, using less sharp curves and having more flexibility.
Any track plan that fits in 4 x 8, 4 x 10 or 4 x 12 feet in H0 scale can be recreated in 30" x 80" in N scale - except you probably can use wider curves - allowing you to run larger engines and longer cars.
2) You can reach across 30" from one side (especially if you stand on something), but not 48".
So an N scale HCD layout can be up against walls on three sides, and only need a 2 foot aisle along one side. Allowing you a far better layout to aisle ratio - the N scale layout takes up 55% of the total floor space, for an H0 scale 4x8 60% of your space need is for aisles, and only 40% is layout.
3) Turning a 4x8 sheet of 1/2" or 3/4" plywood into a table is quite a bit more complex than just putting supports (possibly including shelf supports) under a blank hollow core door, which has built in structural stability.
If one absolutely want H0 scale continuous run loops on a table, and the space one has available for model railroading is the kind of spot best suited for a 4x8 - i.e an area in the middle of a room where a ping-pong table previously resided, then a 5 x 9 foot layout would be a better idea.
If all one has is a small 8 x 10 foot bedroom, it would often be a smarter idea to do an around the walls type of layout - a 4 x 8 in a room that size essentially means that nothing else can be fitted into that room.
This is what I have put (in H0 scale) into a room far too small for a 4x8 foot layout:
Over the layout there is quite a bit of accessible storage, under the layout is more accessible storage and a work desk.
Mind you - I have nothing at all against the concept of continuous run loops of track on a table.
And I am not saying that you cannot make a great looking and interesting to switch 4x8 foot layout. Or that people should never make a 4x8.
But I think that claiming that "there is nothing wrong" with the H0 scale loop on 4x8 foot table format is a statement that is misleading - there are several well known challenges with that format.
For a general discussion of 4x8s vs other footprints, see Byron Henderson's illustrated discussion here:
http://www.layoutvision.com/id28.html
For a step-by-step book on how to create a nice N scale layout (if N scale is an option the thread starter would like to explore), I would recommend Marty McGuirk's "
N scale railroading: Getting started in the Hobby"
Smile,
Stein