Hi roncarter17, and welcome to the forum. Both, Streets & Trips and Street Atlas, are able to modify a plotted route much easier and faster than any other solution. Something that would take you extremely very long time to achieve on a PND (personal navigation device), can be done in most cases by a few mouse clicks on a laptop using Microsoft Streets & Trips.
I'm much more familiar with S&T, so it would be unfair for me to say which program is easier. I know there are many DeLorme fans who would strongly suggest Street Atlas.