Right now I'm having a trip around Montenegro, posting this from a hotel in Jablac. The car is a rent
Mazda 5. It's quite comfortable and has a lot of space on the back seats, but the engine is kinda weak to drive uphill...
If I would be a very rich man and decide to take trip around... wait, what country? If it would be
the same trip like the OP says - this must be the US. In this case, my choice would be...
1991 Chevrolet Caprice Classic. The top version with the 5.7L LT1 V8 engine.
For an epic road trip, I'd take two or three friends and need a car with a big interior space. An American fullsize car would be an almost perfect choice. When I say "American fullsize car", I usually mean the '91 Caprice. I just love it.

This is the one of the most awesome-looking sedans to me ever. This car is pretty common in the United States and I suppose it's easy to maintain there.
If the trip takes place in my home country - Russia, I would pick a different car. I'd drive to visit Karelia, Caucasus, Ural, Siberia, and reach the east coast in the city of Vladivostok, and back... Will have to travel more than 20000 km overall!

And I know a car which will make it fun:
1962 GAZ 22 Volga - the wagon version of the legendary GAZ 21 (which you can see on my avatar).
It's very durable and reliable (like the AK rifle!

), and easy to repair. This might sound weird, but the 1962 Volga's engine is similar to many modern Volga models and GAZelle vans, and it shares many spare parts with them. So spare parts are easy to get.
The ground clearance makes this car driveable on bad roads and even in light off-road conditions. This ability is requied, because "Russia has no roads - there are just directions" (c).
With the payload of 400 kg and a big trunk, it can accommodate a lot of stuff needed for a long trip.

And one more thing:
This tailgate makes a nice table for a field dinner!
