My road course is currently 92' of 2 lane Artin 1/32 track on a 8' x 16.5' table. Copper taped all around so no power taps. Pyramid PS26KX variable power. It used to be 122', but my grandsons (now 6, 4, and 2) couldn't drive it so I designed a layout that, with lowered power, will keep cars in the slot. We run 1/32 and 1/43 cars. The longest straight is about 14' along the back wall.
We also have a scale HO 1/4 mile drag strip from AutoWorld, and a 1/32 scale 1/4 mile made with copper taped Strombecker track and a 12v power supply from an old computer. That drag strip is also measured for a 1/43 1/4 mile, and 1/24 1000 foot races.