Canada
St. John's = 45 - Nice town to visit,downtown is a bit disappointing except for George Street, which is everything it should be. But it is way too spread out, particularly the university and the legislature.
Halifax = 50 - A nice regional centre, with a few good neighbourhoods. Little modern growth in the city, preferring sprawl. Bonus: ferry is part of the transit system.
Quebec = 65 - Wonderful old city, a revitalizing "real" downtown and some good inner nabes, especially between old city and Laval U. Otherwise, more freeways than almost anywhere in NA per km/pop, and horrible, horrible, sprawl.
Montreal = 95 - Toronto vs. Montreal is a tough discussion. Toronto as a whole is more vibrant, has better 'burbs, a better transit system (!), but Montreal has a really solid urban core with a lot that would keep an urbanist happy, and is really a bit more "fun" in a je ne sais quoi fashion, though I'd pick Toronto. If you want ugly suburbs, I might suggest Dollard-des-Ormeaux or Pointe-Claire in the winter.
Ottawa = 65 - Byward Market may be Ontario's best urban space, and the city is kept up nice, a good culture scene, and with a few great nabes. But faceless burbs.
Hamilton = 50 - Great bones, lots of potential. Is what Baltimore is to Washington as Hamilton is to Toronto.
KW = 30 - More exciting than London, at least in the past 5 years. Partly thanks to local intelligentsia and entrepreneurs and hopefully will nail an NHL team. Has a long way to go to be urban and exciting though.
London = 25 - a downtown that has almost been left to rot by suburban-focused city planners, the university almost too far to help. Really, a boring city, which is really unfortunate.
Winnipeg = 55 - Great bones, somewhat underrated. Good culture, some great preserved buildings but would sell is soul for a new hockey arena (as it did). Will lose 5 points if the Asper Museum of Tolerance is built.
Vancouver = 85 - Feels small, but some good nabes and really interesting burbs like Richmond, Burnaby and Surrey. It really is a wonderful setting. Transit and planning seem to match well. There is the smug factor.
Victoria = 50 - Nice, but a bit too twee downtown, but which is healthier than most for cities its size. Nice setting and a good base for a lot of tourism. I can't stand how it tries to market itself as an olde English city, though it can be a pretty city.
US Northeast
Boston = 90 - I'm not sure it's underrated, but it's pretty, with a lot of nice nabes and satellite cities.
Providence = 45 - Actually they've done a really amazing job with their downtown lately. Turn a corner and there's another surprise, downtown is healthier than I expected.
New York = 200
It's New York.
Baltimore = 55 - Underrated city with a large healthy central district that runs from the condoizing, yet authentic Fell's Point through to the small financial district and up to Mount Vernon. Their transit system is a joke, but I think they try to make an effort, and it's easy to get to Washington or anywhere in the Northeast. Good local culture scene. Just watch where you go as you can head into scary areas quite quickly, for which it loses serious points.
Washington DC = 65 - Gets more points in some ways for its planned beauty of its central core, which thanks to tourists, isn't as dead as it should be after hours. But apart from Dupont Circle, Georgetown or U Street, there aren't any neighbourhoods worth writing about. There's the shame of the poor neighbourhoods to the east that are within sight of the Capitol dome. However, the Metro is great, and has some interesting and urbanizing suburbs and satellite cities.
US Rust Belt
Buffalo = 40 - On the plus side, there's great architecture downtown and in the northern nabes (Darwin Martin), there's the Albright-Knox, there's Elmwood Village and Allantown. On the minus side, there's everything else: the comical LRT, the segregation and poverty, the lack of anything new. It's very slowly dying, which is tragic.
Cleveland = 40 - Their metro is almost as comical as Buffalo's. Like Buffalo, there's a few good inner city nabes, the downtown itself is less dead than one might think, but the waterfront is very disappointing and there's a lot of dying inner city and inner burbs. Very slowly dying as well.
Pittsburgh = 65 - Managed to survive the decline of the steel industry by drawing on the cultural and educational legacy of the steel barons to go high-tech to an extent. Beautiful setting, but I think the mountains, while giving you the ultimate entrance to the downtown, break the city up and make it more sprawling than it could be, almost like Sudbury (to a much different scale of course). There's lots I'd still like to see.
Detroit = 35 - Has not managed to survive the decline of the American auto industry. The downtown itself might be light years ahead of what it was in say 1995, but that included some sad, and in at least one case, illegal demolitions. Downtown Detroit is a lot livelier though. Apart from some exceptions like Royal Oak, Dearborn and Birmingham, the suburbs are awful. Culture is good, but not much else. Apart from the area where Hispanics have moved in, it's a sad place.
US South
Atlanta = 25. I am only going by my two hour visit during a lengthy layover at the Delta Hub, but I got out of the metro at the main station and saw nothing that interested me. It really is a strange location for the "capital of the 'New South'". I hear people like talking about Buckhead, didn't visit it though. Not sure if I need another visit to decide if my score is too low.
Rest
Chicago = 85 - The architecture is spectacular, and there is an local infrastructure and building envy. Some nice suburbs and satellite cities (Park Ridge, Oak Park, Evanston). I find the waterfront somewhat overrated compared to Toronto as nice as Millennium Park is. City at ground level though not as vibrant as Toronto. Still booming, but not as fast as Toronto, which I see as it's emerging rival. Loses big points for its segregation.
Las Vegas = 25 - Least urban city I have ever spent any time in, but fascinated me in a macabre way when I was there in 2002.
San Francisco = 90 - SF is probably overrated. It does have one of the nicest inner cities I have seen, the climate is almost perfect, it has some interesting satellite cities, but yeah, I could feel the smug level rising. I had lots of fun, being a transit geek, but I think I could get bored there, like Vancouver.
Los Angeles/Riverside = 80 - LA is just so huge, so cultural (low-brow but also higher brow), I really enjoyed my visit there in 2007. Yeah, it's a city you almost have to drive in, though I spent a day entirely on trains and buses, and it really is a city of distinct neighbourhoods. I could see it becoming more livable, rather than less livable. There's little smugness outside of the entertainment industry.