Agreed...
the 7100 isn't meant for unpaved paths or trails. It's what is called a hybrid, a cross between a road bike and a mountian bike as far as frame gemometry and design, but there the similarity ends. It's not designed for anything rougher than paved bike paths or very smooth and level unpaved paths. They don't do well in gravel or on wood chip coverd paths or on other loose surfaces at all. The 7000 series of bikes make very good and comfortable town bikes for errands, commuting, or just riding around. And they will do fairly well over long distances as long as the terrain isn't to variable, they're not the best climbers, so fairly level routes are best. Don't get me wrong, you can climb with the bike if you're in good enough shape and your legs are strong. But there are better bikes out there for the task.
The Navigator is considered a Cruiser. They are quite a bit heavier built than a hybrid, but are even more comfortable and very durable due to the heavier construction of the frame. Certainly not designed for long distance riding and not designed to be particularly fast. They are basically what the name implies a bike to just cruise around on. They're okay for short commutes, running up to the mini-mart, stuff like that. I work at a Trek dealer and we most often sell the Nav's to folks that hang em on the back of their RV's, haul em to whatever tourist trap they desire and use them to see the sights, run for groceries, etc. The Nav would certainly do better on unpaved bike paths as long as things weren't too hilly, the tires and wheels would lend themselves much better to unpaved surfaces than those that come on the 7100. But the heavy weight of the Navigator would limit you to fairly level areas unless you have legs like the Governer of California and the lungs of a Tour Racer.
Anyway, either bike will do what you are thinking of. The Nav would be better on dirt paths, the 7100 will be faster and lighter on pavement and better for the long distance rides. As trek7100 said, if the majority of your riding is going to be on pavement the 7100 sounds like the better way to go.
Good Dirt