I´d say that really is your choice, but not a bad idea.
I have some more ideas you might try:
I don´t know how you do it, but I find it helpful to add populations, water shaders and other details as a final step, when I am satisfied with my terrain.
concerning the river, as mentioned above the painted shader is a good tool to shape your landscape with much control, for example to add detail to your river. Make sure the preview is finished generating highest detail, then pause it and simply paint in your river rises, depressions, whatever. (there is a brush symbol above the preview, third from the right) you can use these as displacement function for a surface layer then, or to mask layers. You can create an additional powerfractal-terrain and mask it with a simple shape, distance shader, painted or fractal shader to control where it appears.
i just made a simple example.
My best Regards,
J