Really...if you're willing to use a scale model here on Earth you could walk to the (former) planet Pluto, and visit all the other planets along the way.
One way to help visualize the huge distances in space is to imagine a model solar system in which everything is reduced in size by a factor of about a billion. A human on this scale would be the size of an atom, an inch would be about 100,000 miles, and one pace about 36,000,000 miles.
The model Earth would be about the size of--what else--a small blue marble. The Sun would be about the size of your head or a bowling ball, which is a good image because it's dense. The bowling ball that is. The chart above (click to enlarge so you can print it out) shows the distance to each planet in paces. The planets are to scale. If you wanted to go on a star trek, the nearest one (not counting the Sun) would be the same distance as a walk all the way around the Earth.
This space walk works best if you do it on a sidewalk or beach where you can see the whole distance. Leave a rock, stick, or kid at each planet to mark the distance. You're welcome to copy these sheets and print them in quantity for all the kids in the neighborhood or for school class use. Hi-res versions, designed to be printed back-to-back with two folds, are available for free.
Errata: In Fast Facts there is one correction and one change. The Sun is losing weight by the second but it still is 99.8% the mass of the solar system, not 98.8% as stated. Pluto is officially no longer considered a planet, it's a large asteroid; and there is a spacecraft on the way now.