To answer your question directly and with minimal confusion, there are three that I am familiar with, Delorme Street Atlas, Microsoft Streets and Trips and CoPilot. CoPilot was assembled to be very effective for truckers, but if you have a large RV, it may be worth looking at.
The real advantage of running a Laptop Navigator package is that you can to the planning and the on-route navigation with the same device and software. If you buy the package with a GPS puck, you will also need either an inverter or a car-power supply. It will be well worth it. It is very difficult to do in detail planning on a dashboard GPS.
You used to be able to download a two week package of Streets and Trips. That might be good if you still can. IF you cannot, borrow either (better yet) both from a friend. Try to use that package. If you are a very MS oriented person, you may find S&T better. I used to alternate depending on which package I got first at the best price, but S&T was difficult to use for many things I liked to do and SA was not so about 5 years ago I gave up on S&T and now run SA only. I buy a new copy about every other year to keep the charts up to date. It is less expensive without the GPS.
I get asked about this sort of thing all the time. It just may be because I name tag that said "Navigator". We often run two. My wife likes to drive, so I load the day's route to her dashboard unit and I work the the laptop to keep the route current and plan the next day.
Matt