Toronto, Montreal, Quebec by Train

We are thinking of visiting Toronto, Montreal and Quebec this fall and
travel between cities by train. Our plan is to stay in each city 2 days, but
do not want to rent a car. On the internet and in some travel brochures it
seems easy to get around the city, but is it? If you have any experience
traveling by train on your own, we would like your opinion.

- train travel experience
- transportation from airports in Toronto and Quebec city center
- motels/hotels near the train station
- how easy is it to get to city attractions, can we walk or do we need
public transportation
- your recommendation of what to see in each city
- any other tid-bits to help us plan our trip

Thanks in advance,
Don