Help with Montreal/Quebec City itinerary

[Anonymous]

I know this has been asked a bunch of times but I have some specific questions about our travel I'm hoping someone can help with.

We are planning to go to Canada in August. Here is our general itinerary:
Saturday - Fly to Montreal and transfer to Quebec City
Saturday-Wednesday - Quebec City (we have a room at the Hotel Maison du Fort in the Old City)
Wednesday - Return to Montreal
Wednesday-Saturday or Sunday - Montreal (we have a room at the Embassy Suites)

We were originally planning to take the train from Montreal to QC. However, I am realizing that there are only a couple trains a day so if our flight is delayed and we miss the mid-day one, we wouldn't get to QC until like 9 pm. So now I'm thinking we could book our flights DC to QC (which will have a stop in either Montreal or Toronto anyhow) or rent a car and drive. The benefit of driving is we'd have the car for day trips out of QC - like the waterfalls, beach, etc., and could make stops or detours between the two cities. But is it a hassle to drive/park in the city? In general in cities we like not having a car... just wondering if we'd feel that way in QC. We'd probably drop off the car once we got back to Montreal.

Does the itinerary above seem like enough time in each city?

Thanks for any thoughts and recommendations.