Far better to use the 'route tool' within Mapsource (in the toolbar select the icon with three little squares joined by a red line). Click on your start point and then click along your route to define it, once you reach the last point on your route press the 'Esc' key on your keyboard.
If you need to make changes click the 'select tool' (arrow on the toolbar) and select your route by clicking on it, it should then show as yellow rather than magenta. Once you've done this you can click anywhere on the route and drag a new navigation node to an alternate road to change the route. If you click on an exiting node (little black square) you can move it.
To remove a nav. node click away from the route using the select tool so that it return to magenta and then click the node that you want to remove, it should now be yellow with the route remaining magenta. Press the 'Delete' key on your keyboard and a confirmation dialogue will appear, click 'Yes' and the node will be removed and the route recalculated.
One of the easiest ways to plan a route is to just define the start and end points using the 'route tool' and then use the 'select tool' to refine the route between these two points.
It's best practice to go through the route checking the nav. nodes you've defined in close detail as it's easy to place them just off the route if there's another road close by or on the wrong side of a dual carriageway.
When plotting a route through towns and cites drop your nav. node on the road out of town first, that's all you might need to do. Depending on your unit there is a limit to the number of navigation nodes although I think this is around the 500 mark (on my Quest) which is more than you should ever need.
If there are POIs/waypoints that you do want to visit just select those within your route.
Break your tour up into day long routes (or hotel to lunch and then lunch to hotel, i.e. two routes) rather than have the entire tour as one big route. This way any recalculation is quicker and it allows you to have alternate routes loaded if you so desire. Don't bother to try and get the unit to do ferry crossings, have one route to the departure port and another starting at the arrival port going onward.
If sharing your route any riding buddies they will probably need to recalculate the route in Mapsource if they are using anything other than the exact same version of City Navigator as you.
