If you have the time, Hwy 138 from Montreal to Quebec city, and Hwy 132 from Quebec City to Riviere du Loup are very picturesque. However, both are 2 lane, and go through all the old towns & farms along the river.
If a choice has to be made in the interests of time, the preferale and more picturesque route would be 132 from Quebec City to Riviere Du Loup. L'Islet has a wonderful old maritime museum, St. Jean Port Joli has several wood carvers who make a style of wood sculpture unique to Quebec and not found anywhere else. Knock offs sold in the Old Town of Quebec City should be avoided and the real thing should be sought out in Riviere Du Loup.
The town of La Pocatiere has a historic museum of of the area located in the old College, and the town of Kamouraska should be visited to experience the architecture and ambience of old Quebec. Kamouraska also boasts numerous good restuarants as well as a fabulous bakery cross from the Church. Nearby is a famous seafood store selling eels and smoked salmon. If you are really lucky in Kamouraska, ask if the farm tractor museum can be seen. It's a private museum, but sometimes the owner will takes visitors on a tour.
Between La Pocatiere and St. Denis is a cut off that takes you to the old Quaie or pier at Riviere Ouelle where you can see the river, which is 35 miles wide at that point and has tides. You need to ask about the vieux quaie or the old pier, because it is not in the town of Riviere Ouelle.
However the town of Riviere Ouelle has a great campground with good hookups and it is located on the river side, allowing easy day trips to all the places I've mentioned.
In the area of La Pocatiere you will hear motors whining in the background in the fields. These are the harvesters of peat moss, and these companies export peat moss all over the world including most of the supply in the U.S.
Good grocery shopping can be done in La Pocatiere where there are several large super markets.
