I always use Google Maps to see what routes it will suggest. You usually get 3 choices. You can shift the route to go where you desire quite easily.
I then print out the route to take along for the trip.
I now use a NUVI 2589LMT when driving. It has traffic, and map updating.
and "yes" the routes it chooses are generally not the route I prefer. I just start out and go the route I want. Just ignore the GPS when it differs from your intended route. The new Garmin GPS's will quickly recalculate the route after a mile or two and eventually follow your choice.
States and counties are not very good with keeping mapping companies up to date on construction, but the traffic feature does work for re-routing if the delays on the current route add to much time delay.
I have found in most cases that when the GPS re-routes on my intended route that the arrival time listed gets moved up earlier.
Anyone who travels and does not carry maps for the states travelled is just asking for trouble. Maps are usually free at nearest rest-stop after entering a new state. GPS's are an excellent tool when used correctly.
They are not for the "clueless" who can't read a map or travel without one. It should be noted that when any of us plans our own route for use on a GPS that we may run into construction problems and either change the route of endure long delays.