Terrence you can do a lot in a little space. Here is what a came from at the old house. Its a 10 by 10 room but with doors and such I was limited to 10x8.
As you can see I really stuffed it in there! My trains were chasing their tails but I did it anyway. Now that I have this new room (which is immense compared...) my trains really stretch out and are much more enjoyable to watch. I actually have two running on the mainline in the pictures above due to it taking so long for the train to come back around! Ha ha. 12x9 might not seem like a lot, but when I was at 10x8 I would have killed for another 1 ft by 2 feet! And if you really want to see what you can do, put a drawing with the room dimensions up on this sub forum and watch guys like Obsidian and maybe me and some others go wild. With elevation changes and multiple levels, you can squeeze in as much as you want (see pics above).