I use both Google Maps and Good Sam Trip planner for the perfect route planning. What the Goodsam Trip planner brings to the table is its integration with partner Garmin's routing software and that products knowledge of truck/RV road restrictions. My method goes like this:
RVParkReviews and Google Step - First I start with rvparkreviews.com to pick my most likely stops for the trip (i.e. miles between, review rating etc.). When I get the right park, I paste the address into Google Maps and I just keeping repeating the process as I build out the trip. The Google Map strength is the ability to zoom down on satellite view and street view and see exactly where I'm going.
Goodsam Trip Planner Step -Next, I start a new trip in the GS Planner and paste in each of the park stops I planned in step one. Because GS partners with Garmin, the GS Planner will expose any low underpasses, tunnel restrictions, etc. A good example is our current planned trip that includes a route from Mystic Connecticut to Liberty Harbor RV in New Jersey. GS Planner showed me that Google had me on a bridge that doesn't allow RV's, a tunnel where RV's are prohibited, and a section of freeway for car's only. GS Planner allows you to drag points to force a routing around those trouble spots.
Google Maps Revisioning - Next I go back over to the Google Maps tab and make the same re-routes that GS Trip Planner/Garmin indicated. I use the zoom and street view to check out the new routes and in the example of my trip to Jersey/NYC, I used street view to drive the freeway to see what my exits and city street turns look like.
Google Maps Revisioning - Once your google map is set, choose the option to send to your mobile phone then you'll see an option to also email the map to yourself. I do both phone and email. While traveling if I click the phone message, it brings up Google Maps mobile (map and directions). If we are hotspotting the cell phone, we can go into email and click the map link for a bigger screen view.