Depending on where in the area you are, ie where the 1.5 hours would start from, the Potomac above Great Falls, the main stem Shenandaoh and the Rappahannock are the best rivers for traditional float trips. These are smallie, carp and to a much lesser extent musky waters. Below the fall line, the rivers are less float trip friendly. You will find campgrounds on them, but I don't know if the distances between them are reasonable for that. In the tidal part of rivers you will find stripers, largemouth bass, snakeheads, white perch and blue catfish.
Happy to go into more detail if you have questions about a particular river.