For hotels, check out these:
Ace Hotel $95
Jupiter Hotel $94
Inn @ Northrup Station, Sheraton Four Points Downtown and Hotel deLuxe are sold out. Other hotels like the Lucia have higher prices that I remember, I guess though it is peak season.
I'd say the Ace is your best bet, on hotels.com they have a small 200 sq ft room with 3 bunk beds with bath for $95/night (but read closely because some have shared baths and/or bunk beds that may or may not be what you want). The Ace is in a great location between the core of downtown and the Pearl and right on the streetcar. The other is the Jupiter, the plus to it is the Doug Fir Lounge but its on the other side of the river from downtown and its a party motel (again depending on whether you see that as bad or good).
Then again as a high rolling Canadian with an excellent exchange rate you could go for a top notch landmark hotel
It sounds like you have a pretty good understanding about the Pearl and SoWa. Be sure to check out the South Waterfront Discovery Center with master plan model at the corner of Moody/Bancroft several blocks south of the u/c towers. Also check out the river front walkway, its still a work in progress however. For the Pearl, check out the Brewery Blocks (11th/Couch), North Park Blocks, 13th Ave., Hoyt Street Yards/Jamison Square (new part) as well as the heart of the neighborhood around glisan/11th. As far as urban infill, these are primarily located on the major streets on the inner Eastside, streets such as Hawthorne, Belmont, Mississippi, NE Broadway, Divison/Clinton, Alberta etc., few (if any) are further east of say, 50th street.
Good examples of Suburban TODs are on the Westside MAX line west of the Beaverton Transit Center, in particular the Beaverton Round (Beaverton Central Station), Orenco Station (the famous part is on the north side of the MAX station but theres also quite a bit just south of the station). In Portland theres a great HOPE VI project in North Portland and on the #4 bus called New Columbia (30 min bus ride from downtown).