It's an interesting idea. When I look at Google Maps street views, it looks like a lot of busy street scenery, so it depends on what you are after.
As another idea, you could go into Jardin del Turia and walk the paths that run along Calle de Castro and Calle de Pintor Lopez, which are quite lovely. There is also a dedicated cycle path for 8 or 9 kilometers, through the center of the park.
If you want to see more city sights, I would be inclined to criss-cross and weave a bit through the center. Perhaps one route from Torres de Serranos to Estacion del Norte - about 1.5km - picking and choosing your route through sights of interest. Another criss-cross route might be from Torres de Quart across to Porta de la Mar - roughly 1.7 km. Or further, to the Museum of Sciences.
If you are interested in seeing some neighborhoods, I might walk a couple of streets in from the main ring road thoroughfares. As an example, I walked back from the Museum of Sciences along a road that parallels the park, but in a few streets, and found that a quite interesting route through residential neighborhoods filled with shops and restaurants.