Yeah, I live in YOW and take VIA trains a lot. IMO, travelling with lots of luggage can be a challenge. Try VIA 1 and/or hire a porter in the station.

The Toronto Int'l Film Festival is on in September. If the dates overlap, accommodation can be a challenge (PM me if this is a thing).

I agree with the GG thing and it can become a bit of a theme.......The GG lives in Ottawa, and that time of year you can visit the official residence for a tour. Either book on line - or - just show up.

Parliament Hill is kinda like the NPS in the US. Show up at 09:00 to claim free tour tickets (if not, they are all gone by 13:00).