I'm of the opposite opinion.
The Sheraton Ottawa is a completely crappy hotel. Their level of crappiness is a little better now since all floors and rooms have been refurbished (kind of) and offer the Sweet Sleeper bed. However, the rooms are quite dark and the lighting isn't good if you want to do work. I've stayed on the "Business" floor and other floors. The air conditioning unit is a relic from the 60's and is very susceptible to outside noise. You want to set a temperature? Forget it. There's only 2, hot and cold. And.. you get neighbours on all sides of the hotel which can stare right into your room.
I feel the Westin is a far superior hotel. Much larger rooms or it feels that way since it's not as dark. Great a/c controls and the connection to the mall is great. Yes, not walking outside in sub-zero temperatures is a definite plus. Some people have reported service probs with the Westin but I've never had any problems myself.
I'd stay at the Westin a lot more but the Sheraton is much cheaper. Since I'm a Starpoints whore
, I reluctantly stay at the Sheraton more often.