Either Strips and Treets or Street Alas will do everything you are looking for and are not one bit internet dependent. I traded off between the two for years but later found I outgrew S&T. Both will let you plan a multi-day excursion with diversions and stops. Both will tell you where to look for an overnight location or a fuel stop. If you want a day longer or shorter, they can accommodate that, but both are looking for a day of given length as either miles or hours.
If you buy S&T, get their GPS with it. It used to be incapable of using any other (and only barely with their own).
Both can use overlays that you can download at the Discovery Owner's website. These will get you more information than you can handle. If you want to run the laptop traveling, remember to pick up something that will power it underway.
Matt
