This is an interesting question, Boomer. The best solution, it seems to me, is to convert Route Stops to Pushpins. Unfortunately, that is not as easy as it should be. Some time ago, I added this to the wishlist for future S&T features.
However, there is a possible workaround in S&T 2010 that I do not think would not be doable in earlier versions. It involves the new capability to rename Route Stops.
As you probably know, there are two ways of looking up an address: in the search feature of the Advanced Toolbar; and in the search box of Route Planner. The difference between the two is that the former will automatically create a Pushpin when you accept the search findings whereas the Route Planner will not. It will just put the address into the route. So, to create Pushpins you must get the addresses (one at a time, unfortunately) into the Toolbar search window.
The way to do that with pre-existing route files is to open the old route in S&T 2010 and then, one by one, select the Stops, right-click to get to the Rename function, click [Alt-C] to copy the highlighted address in the Rename box, go to the Advanced Toolbar search box and click [Alt-V] to paste the address into the box. Then, accept the search and a Pushpin will be created and the map focus will be moved to its location. Note that you can then rename the Pushpin to something like the client name or something else useful.
That new Pushpin will now be in your "My Pushpins" set and you may want to create new sets and re-organize the sets and the Pushpins to your needs. Obviously, you will want to save this. But once you have done this conversion and saved the Pushpins, you will have them "forever." Once you have your target Stops converted to Pushpins you will have a great deal of routing flexibility.
I hope this is of some help to you.