I'm sure there's a smarter solution but I would just back into it by picking a town on Interstate X that seems like it MIGHT be ten hours' drive from Town A, seeing how close my guess was, and then repositioning Google Maps until I found the one that really is at 600 miles.

Yeah -- that's kind of what I was trying to avoid.

http://www.mezzoman.com/?

oh, n/m, I misunderstood the question. You want an electronic way to do the old paper map trick of drawing a circle of radius r and seeing where it intersects.

Not to be an ass, but might I suggest a paper map? Or does it need to be exact?

Paper map FTW. Sometimes good ol'fashioned paper really is the best solution, at least until someone makes an app for that.

You could use Google maps for this fairly easily. If you use the Directions, you could add your starting and end points. Then you can right-click and "Add a Destination" about where you think it may be the right point. It will quickly show you how far it is for that leg of the journey. You can change (drag) the route or drag & drop the pointer to see how that it affects the distance. I don't think this is exactly what you want but it's pretty quick to adjust so if you don't find something better, it should work ok.

There's also a measuring tool in Google if you're signed in to an account. It's the little ruler icon down in the bottom left-hand area by the legend. It will show you as-the-crow-flies distances. The Directions above will stick to roads so is probably better.

The drawback of the paper map is that I don't have one here at my desk on this day when I am sitting here bored and am wanting to plan my trip.

How about this: GPS visualizer.

Under "Draw range rings around a point" put in your point A, and the range, and there you go.

It doesn't get you X miles on interstate Y, but it does get you X miles away from point A.

I'm curious about your trip planning ...are you just looking to go somewhere 600 miles away? How did you arrive at this specific problem?

"600" was partly hypothetical, but it's also the outside limit of what I think we'll be willing to drive in a day. So I wanted to look at lodging options in a variety of places that are more or less 600 miles from Las Vegas and/or Flagstaff. However, a) there's a lot of empty interstate in that part of the world and b) I don't like staying in shitty motels, so I was trying to do some preliminary research on towns where we might be able to stay in a not-shitty motel after leaving Las Vegas on the way to Dallas (on one of two routes).

There are a whole bunch of variables. It was easier to ask for mapping tips than to ask for suggestions about where to stay.

This thing basically does it. You can put in an address or zip code and it will draw you a circle, sort of, on a map. Those guys have a ton of other weird and neat apps that do cool things with geolocation stuff and this page has some other sweet examples.

Thanks, Jessamyn, that was helpful.

By the way, just discovered wunderground's Road Trip Planner -- very cool. Gives you temperatures and weather conditions along your route.