OK, now to Zippy's question. I think the amount of mileage a day depends on a number of factors already listed. On interstates across states like IA and NE, one can make pretty respectable time (maybe 400 miles per day). Get on secondary roads in mountainous terrain and you definitely need more time (sometimes 200 miles can take five or six hours). Many will say they do these kind of trips w/o reservations, but we've found that the best campsites get booked early. Take Yellowstone for example. If you don't get a reservation in the park, you spend a lot of time commuting every day. Glacier is a different matter as many of the cg's there are first come, first served. Do check on cg's in Banff and Jasper as they also tend to fill certain times of the year.