Thanks for the replies and advice everyone! We're trying to pin down a definite route so we can figure out where we'll be stopping, find hotels that will take the dog, etc. We do plan on taking 6 days for the trip (about 500 miles a day). We are NOT experienced roadtrippers. The only long trip we've really done was Seattle to Phoenix in 2 days (stopping in SLC). There's no way we're going to try to do that many miles per day on this trip!

I did some looking around on different sites - Mapquest, Yahoo, Google, Rand Mcnally - and got several routes.

They all show us going from Seattle to Billings on I-90. Then one route takes us north on I-94 to Fargo, Minneapolis, Chicago, down to Indianapolis, and over to Charleston. I would think we'd want to avoid Chicago though, so I'm not sure about that option?

The others show us staying on I-90 to Sioux Falls and then either going down I-29 and over on I-80 to DesMoines, and I-74 to Peoria, Indianapolis, Dayton, Charleston

or

From Sioux Falls, staying on I-29 down to Kansas City, over to St. Louis, Louisville, Charleston.

Do all of these seem okay? Advantages or disadvantages?? A few of you guys mentioned going down to SLC and over on 80 through Nebraska, but the websites I tried didn't show that route and it looks longer on the map. Are there any particular advantages to going that way?

My wife and I are both total wimps about heights and mountain roads with terrible overhangs! Traffic doesn't bother us so much since we're used to driving in Seattle - but then we haven't driven a moving van with a tow dolly around Seattle!

Thanks for any further advice - we really appreciate the help.