I stay at the Ottawa Marriott at least once a month. The staff is generally very pleasant and accomodating, the pool is nice, the gym well equipped (and not very busy in the evenings). The one time I tried the Jacuzzi, it needed cleaning and I haven't tred since. The restaurant in the lobby is so-so, the rooftop restaurant better - but more expensive.
Heidi, who staffs the Concierge lounge at night, is one of the best things about the hotel. I have rarely met a hotel employee who is so solicitous about her clients and who, after the first time, remembers your name and whether you want 2% or skim milk with your favourite cookies.
The area is pretty quiet at night but Bank Street restaurants (pretty ordinary) are only a block away and it's a 15 minute walk to the Market where the choice is endless.
The Courtyard's right in the Market - and the staff there are great, too.